US3706998A - Multiple interleaved phased antenna array providing simultaneous operation at two frequencies and two polarizations - Google Patents

Multiple interleaved phased antenna array providing simultaneous operation at two frequencies and two polarizations Download PDF

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US3706998A
US3706998A US112395A US3706998DA US3706998A US 3706998 A US3706998 A US 3706998A US 112395 A US112395 A US 112395A US 3706998D A US3706998D A US 3706998DA US 3706998 A US3706998 A US 3706998A
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radiating elements
radiation
array
radiating
elements
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US112395A
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Burrell R Hatcher
Aldo R Miccioli
Max C Mohr
Edward J Sheldon
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Raytheon Co
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Raytheon Co
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
    • H01Q25/001—Crossed polarisation dual antennas
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/44—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
    • H01Q3/46—Active lenses or reflecting arrays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/40—Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
    • H01Q5/42—Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements using two or more imbricated arrays

Definitions

  • ABSTRACT A phased array antenna including within its single electromagnetic radiating aperture two or more groups of radiating elements, each group of radiating elements being distinguished by the polarization and frequency spectrum of its radiation.
  • the radiating elements of each group are of sufficiently small physical size compared to their free space wavelength to permit their being interleaved among the radiating elements of the other groups in a configuration whereby each group of radiating elements has approximately the same control of the beamwidth and the steering of its beam of radiation as would be the case if only one of these groups were present.
  • This invention relates to antennas having a plurality of electromagnetic radiating elements, and more particularly, to the utilization ofa single radiating aperture having elements of differing characteristics to provide a capability to operate simultaneously at more than one frequency band, polarization state and scan sector or any combination of these three.
  • An installation employing two or more phased array antennas is required for certain applications as in the situation where signals of differing carrier frequencies or polarizations are required to be transmitted to a single target vehicle.
  • Such installations typically require a number of support structures for the individual phased array antennas which entail considerable weight, space, and auxiliary equipment.
  • an antenna having a single electromagnetic radiating aperture which combines the features of a plurality of individual antenna arrays. These features include, for example, a frequency diversity capability and a capability to transmit in the various frequency bands and in the polarizations of the individual arrays as well as means for steering each of the plurality of beams of radiation.
  • This aperture need be no larger than the apertures of the largest individual antenna since each beam of radiation is generated independently of the other beams and therefore the aperture dimensions of the individual array are adequate to form the beam.
  • a single aperture antenna of this sort is particularly advantageous for mobile applications, for example, where a phased array radar is to be mounted on a space vehicle or aircraft. In addition to the savings in space, weight, and expense, this antenna also provides a common axis for the plurality of beams of radiation.
  • the interelement spacing that is, the distance between centers of the radiating elements of an individual array cannot be increased to provide spaces for other radiating elements, because the interelement spacing plays a critical role in forming the beam of radiation. For example, an increase in the interelement spacing alters the beamwidth and such increase can be great enough to produce grating nulls in the antenna directivity pattern, particularly at large scanning angles. It is, therefore, desirable to provide an improved antenna array comprising electromagnetic radiating elements with radiation characteristics similar to those of two or more individual arrays, and having an antenna radiating aperture whose physical size is no larger than the radiating aperture of the largest of the individual arrays.
  • an antenna array is constructed of electromagnetic radiating elements drawn from two or more individual arrays of radiating elements wherein each of said individual arrays is identified by the characteristics of directivity pattern, polarization, and frequency spectrum of the beam of radiations which it generates.
  • a group of electromagnetic radiating elements drawn from each of said individual arrays are dielectrically loaded to be of sufficiently small physical size compared to their free space wavelengths to permit their being interleaved among the radiating elements drawn from each of the other individual arrays, and the configuration and spacing of the interleaved radiating elements is such that the above characteristics of the individual arrays are retained.
  • the interelement spacing namely, the spacing between centers of the radiating elements drawn from any one group, is typically approximately one-half the free space wavelength of the radiation generated by these elements. Accordingly, each radiating element of each of said groups is constructed with a physical size which is smaller than the interelement spacing to permit the radiating elements to be spaced in said array with the aforementioned one-half free space wavelength spacing between centers.
  • the polarization of the radiation which is characteristic to the radiating elements of one group be orthogonal to the polarization of the radiation which is characteristic to the radiating elements of the second group in order to minimize a cross coupling between the two groups of radiating elements.
  • FIG. 1 is an isometric view of one embodiment of this invention having a reflector-type optically fed antenna array, the antenna array having electromagnetic radiat' ing elements of two different frequencies, said elements being interleaved so that the spacing between centers of the lower frequency radiating elements is equal to twice the spacing between centers of the higher frequency radiating elements;
  • FIG. 2 is an enlarged fragmentary isometric view of the antenna array taken along the line 2-2 of FIG. 1;
  • FIG. 3 is an isometric view, partially cutaway, of one embodiment of a radiating element of the array of FIG. 1 wherein the radiating aperture has a diameter which is approximately 0.2 wavelengths of the radiation transmitted by this radiating element;
  • FIG. 4 is a fragmentary perspective view of a portion of an alternative embodiment of the interleaved array of FIG. 1 wherein the spacing between centers of the lower frequency radiating elements is equal to the spacing between centers of the higher frequency radiating elements;
  • FIG. 5 is an enlarged fragmentary perspective view of a portion of an alternative embodiment of the interleaved antenna array of FIG. 1 wherein the spacing between centers of the lower frequency radiating elements is greater by a factor of 3 than the spacing between centers of the higher frequency radiating elements;
  • FIG. 6 is an enlarged fragmentary perspective view of a portion of an alternative embodiment of the interleaved antenna array of FIG. 1 wherein the spacing between centers of the lower frequency radiating elements is equal to twice the spacing between centers of the higher frequency radiating elements, and wherein a lower frequency radiating element is mounted beneath and coaxial with a higher frequency radiating element; and
  • FIG. 7 is a fragmentary view, partially in section, ofa higher frequency coaxially mounted radiating element and its mounting strut.
  • phased array antenna 10 which includes an interleaved antenna array 12 which serves as a reflecting surface for directing electromagnetic radiation to the feed horns l4 and 16 for receiving said radiation, and during transmission, for collimating the radiation from the feed horns 14 and 16 to form individual beams of radiation.
  • the phased array antenna 10 is adapted to operate in a novel manner simultaneously with radiation at two frequencies and two polarizations.
  • the higher frequency radiation has a circular polarization of one sense, that is, clockwise or counterclockwise and is reflected from the smaller radiating elements 18, two of these elements being designated 18A and 18B.
  • the lower frequency radiation has a circular polarization of the opposite sense in order to minimize cross-coupling between the higher and lower frequency radiating elements and is reflected from the larger radiating elements 20, one of which is designated 20A.
  • the antenna 10 operates in the manner of phased array antennas where each group of radiating elements 18 and 20 imparts a phase shift to radiation emanating from the high frequency born 14 and the low frequency horn 16 to direct it in the desired direction.
  • the radiating elements 18 and 20 direct the received radiation which is incident upon the face of array 12 in the directions respectively of the feed horns 14 and 16.
  • the amount of the phase shift is controlled by computer-generated signals, not shown, applied to each of the, radiating elements.
  • the feed horns 14 and 16 are of different physical dimensions to accommodate the two frequencies, the horn 14 having a smaller cross section to operate at the higher frequency and the born 16 having a larger cross section to operate at the lower frequency. Electromagnetic energy from each horn illuminates the entire face of the array.
  • the antenna 10 is provided with a support structure comprising a metallic mounting plate 22 and supporting struts 24.
  • the metallic mounting plate 22 also serves as a ground plane for the radiation, and can be hexagonal, as shown, or of any convenient form, such as circular or square, and is provided with apertures to receive the radiating elements 18 and 20, and hold these elements 18 and 20 spaced in a manner to be described.
  • the struts 24 support the mounting plate 22 and also support transmitting and receiving equipment contained in metallic cabinet 26.
  • the feed horns 14 and 16 are connected to the transmitting and receiving equipment and extend outwardly from the electronics cabinet 26.
  • the feed horns are rigidly attached to the mounting plate 22 by means of a bracket 28. As shown in FIG. I, the higher and lower frequency radiating elements 18 and 20 are uniformly distributed throughout the interleaved array 12 so that the high and low frequency beams of radiation generated by the antenna 10 are coaxial.
  • the arrangement and means for mounting the radiating elements 18 and 20 are shown in FIG. I and in greater detail in the enlarged fragmentary view of FIG. 2.
  • the radiating elements 18 and 20 are arranged in a configuration, as' seen in FIG. 2, in which each of the larger size, lower frequency elements 20 abuts three smaller-size, higher frequency elements 18 located in equally spaced-apart relation around the periphery of said larger element 20.
  • lines, now shown, connecting the three elements form an equilateral triangle or cell.
  • the smaller size, higher frequency elements 13 are located with respect to each other at the intersections of three sets of parallel lines, not shown, which form a grid having cells, each of which is in the form and size of said equilateral triangle.
  • the spacing between the centers of the higher frequency radiating elements 18 is approximately one-half wavelength of the radiation which is transmitted by the radiating element 18.
  • the higher frequency is, by way of example, equal to twice the lower frequency and therefore the lower frequency radiating elements 20 are shown with I060l l 0138 a diameter that is twice as large as the diameter of the higher frequency elements 18.
  • the lower frequency elements are similarly positioned at the intersections of three sets of parallel lines, not shown, which form another grid having equilateral triangular cells whose sides are twice as long as those of the aforementioned grid for the higher frequency elements 18, so that the spacing between centers of the lower frequency elements 20 is twice as large as the spacing between centers of the higher frequency elements 18.
  • a spacing ratio which is the ratio of the spacing between centers of the larger size, lower frequency elements 20 to the spacing between centers of the smaller size, higher frequency elements 18.
  • the spacing ratio is 2:1, so that the high and low frequency beams of radiation can be steered over approximately the same range of beam steering angles that do not introduce grating nulls.
  • the radiating elements 18 and 20 are affixed with their axes perpendicular to the mounting plate 22 by mounting bolts 30, one of which is designated 30A.
  • the bolts 30 are tightened against the lips 32 of recessed portions 34 of a higher frequency radiating elements mounting flange 36 and are similarly tightened against the lips 38 of recessed portions 40 of a lower frequency radiating elements mounting flange 42.
  • the lips 32 and 38 and the recessed portions 34 and 40 have dimensions which permit a single mounting bolt, such as bolt 30A, to be utilized at the point of proximity between two abutting radiating elements such as the elements 18A and 20A.
  • Each of the higher frequency elements 18 are spaced in the aforementioned configuration to be equidistant from each neighboring high frequency element.
  • FIG. 2 there is also shown a cartridge or case 44 and matching structure 46 for each higher frequency element, and a cartridge or case 48 and matching structure 50 for each lower frequency element which are described below.
  • FIG. 3 there is shown a detailed isometric view, partially cut away, of an individual high frequency radiating element 18.
  • the radiating element 18 is encased in a metallic cylindrical cartridge 44, preferably of Mu-metal, which serves as a magnetic shield and as a support structure for the components of the radiating element.
  • the diameter of the radiating element is approximately 0.2 wavelengths of the freespace radiation which is transmitted by this radiating element. This diameter is substantially smaller than the diameter of approximately one-half wavelength customarily employed for cylindrical elements in phased array antennas.
  • the front ends of these elements are equipped, as shown in FIG. 3, with a dielectrically loaded cylindrical waveguide 52 and matching structure 46 which provide effective radiation from these smaller radiating apertures.
  • the matching structure 46 has the form of a cylindrical tubular segment or annulus of a ceramic material, such as for example alumina, to provide for radiation from a small aperture, in a well-known manner, by generating higher order waveguide modes.
  • This type of matching structure is particularly adapted to receive radiation over a range of scan angles which is characteristic of phased array antenna operation. Electromagnetic radiation propagates within the ceramic material of the matching structure 46 at a slower speed than in air. Due to the slower speed of propagation, the relatively small dimensions of the ceramic matching structure 46 are sufficiently large to support a number of waveguide modes which include the dominant mode and higher order modes. The guide wavelengths of these modes depend on the scan angle, polarization and frequency of the radiation transmitted by the antenna array 12.
  • the matching structure 46 is typically constructed so that the difference between its inner and outer radius is equal approximately to two wavelengths of the radiation transmitted in a medium of this type of ceramic material; and the axial length of the matching structure 46 is typically four wavelengths of the radiation which is transmitted in a medium of this type of ceramic material.
  • the matching structure 46 is reciprocal so that multiple modes are generated both with incident and transmitted radiation.
  • the combination of the dominant plus the higher order modes of radiation provide for a radiation efficiency and bandwidth from a small aperture, such as the present radiating aperture having a diameter of approximately 0.2 wavelengths of the free space radiation, which approximates that of a radiator transmitting in the dominant mode from an aperture having a diameter of approximately 0.5 wavelengths of the free-space radiation.
  • the matching structure 46 Upon receiving radiation, the matching structure 46 provides the aforementioned modes, and with the aid of the dielectrically loaded cylindrical waveguide 52 and a wellknown impedance transformer 54 which give differential phase velocities to these waveguide modes, the plurality of these waveguide modes are combined to produce a single circular waveguide mode, the TE mode at the junction of transformer 54 and phase shifter 56. This mode is desirable since it facilitates operation of the phase shifter 56.
  • the circular waveguide 52 also compensate for the mutual coupling between the individual radiating elements which transmit radiation of the same frequency, so that each of these radiating elements can impart the desired phase shift to the radiation essentially independently of the phase shift being imparted by the other
  • the section of circular waveguide 52 is adjacent the matching structure 46 and is dielectrically loaded with materials having different dielectric constants in order to impart the aforementioned differential phase velocities to the various waveguide modes. While several different dielectric materials can be used, it has been found by experimentation that the use of two dielectric materials, quartz and ceramic for example, is sufficient to provide the differential phase velocities.
  • a quartz rod 58 is disposed along the axis of the waveguide 52 and is mounted within a ceramic l060l l 0139 cylinder 60, the dimensions of which will be described.
  • the ceramic cylinder 60 is supported by the metallic case 44 which also serves as the waveguide wall.
  • the use of the two different dielectrics results in a nonlinearity in the differences between the phase velocities of the various waveguide modes whereby the several wavefronts of each of these modes from the matching structure 46 advance along the waveguide 52 to reach the terminus of the waveguide 52 with a small difference in their respective phases.
  • the difference in the phases of their respective wavefronts is further reduced in the impedance transformer 54 so that a single wavefront, that of the TE mode, is launched into the phase shifter 56.
  • the difference between the outer and inner radii of the ceramic dielectric cylinder 60 is typically one wavelength of the radiation transmitted in a medium of this ceramic material; the radius of the quartz dielectric rod 58 is typically two wavelengths of the radiation transmitted in a medium of this quartz material; and the axial length of the circular waveguide 52 is typically eight wavelengths of the radiation which is transmitted in a medium of this quartz material.
  • the impedance transformer 54 which is positioned between the dielectrically loaded waveguide 52 and the phase shifter 56 is in the form of an annulus of dielectric material, preferably of ceramic, supported within a metallic support 62.
  • the ceramic annulus of the impedance transformer 54 and the metallic support 62 act as a short section of circular waveguide which launches the TE mode into the phase shifter 56.
  • the difference between the outer and inner radii of the ceramic annulus of the impedance transformer 54 is typically four wavelengths of the radiation which is transmitted in a medium of this ceramic material; and the axial length of the impedance transformer is typically one and one-half wavelengths of the radiation, which is transmitted in a medium of this ceramic material.
  • the compensation for the mutual coupling between radiating elements transmitting at like frequencies of radiation is effected by virtue of the fact that the combination of matching structure, dielectrically loaded waveguide, and impedance transformer matches the higher order waveguide modes induced by radiation incident upon the antenna array over the usual range of scanning angles typical of phased array operation. Accordingly, waveguide modes induced by radiation from adjacent elements are essentially not propagated through the dielectrically loaded waveguide and impedance transformer to the phase shifter.
  • the construction of the radiating element shown herein provides a relatively broad bandwidth in excess of approximately 8 percent.
  • each of the radiating elements 18 and 20 provides the dual function of reflecting and imparting a phase shift to the incident radiation.
  • the radiating element 18, as shown in FIG. 3 contains phase shifter 56 terminated by a short-circuit in the form of a metallic cap or disk 64 which reflects the radiation.
  • the phase shifter 56 has essentially the same form as that disclosed in the patents to Francis J. OHara and Howard Scharfman,
  • the phase shifter 56 comprises a waveguide structure having a dielectric cylinder 66 enclosing an inner core in the form of a ferrite rod 68, a metallic conducting cylindrical wall 70 typically formed by depositing silver on the outer surface of the dielectric cylinder 66, and a control coil 72, coaxially mounted with the ferrite rod 68 and enclosing the cylindrical wall 70, which controls the magnetic state of the ferrite rod 68.
  • phase shifter responds to a circularly polarized wave of one sense only, and thereby minimizes cross-coupling between radiating elements which respond to circular polarization of the opposite sense.
  • the control coil 72 is connected via a pair of leads 74 to a coil driver circuit, not shown, of a standard well-known form, which is energized through pins 76 in the back end of the radiating element 18 in a well-known manner to provide the amount of phase shift required for a desired beam scanning.
  • the cylindrical wall 70 of the phase shifter 56 is supported at its front end by a portion of the metallic support 62 and at its back end by an axial extension 78 of the short-circuit cap or disk 64.
  • computer generated signals are applied to the pins of the radiating elements to energize the coil driver circuit, not shown.
  • the coil driver circuit supplies current to the controlcoil to provide the magnetic field in the ferrite rod which, in turn imparts a phase shift between the incident and reflected radiation.
  • the high frequency elements and the low frequency elements of FIG. 1 receive separate sets of computer generated drive signals so that high and low frequency beams of radiation can be directed independently of each other.
  • the matching structure, the dielectrically loaded cylindrical waveguide, and the impedance transformer function in combination as a unit which provides a broadband impedance match from the radiating aperture at the matching structure to the phase shifter, and also compensates for mutual coupling among adjacent radiating elements.
  • FIGS. 4 and 5 there are shown two alternative embodiments of the present invention in which the radiating elements 18 and 20 are interleaved in alternative configurations. These configurations provide a spacing between centers of the higher frequency radiating elements 18 which is less than or approximately equal to one-half the free space wavelength of the radiation transmitted by element 18, and a spacing between centers of the lower frequency radiating elements 20 which is less than or equal to one-half the free space wavelength of the radiation transmitted by element 20.
  • the diameter of each radiating element in FIGS. 4 and 5 is approximately 0.2 wavelengths of the free space radiation transmitted by that radiating ele ment.
  • FIG. 5 a perspective view of a portion of an interleaved antenna array wherein the radiating elements 18 and 20 are affixed to a mounting plate by bolts 30 in contact with the mounting flanges 36 and 42, said mounting plate being designated by 80 in FIG. 4 and by 82 in FIG. 5.
  • the smaller size higher frequency radiating elements 18 are located at the in tersections of a grid of equilateral triangles, not shown, the same grid, hereinafter designated the reference I060l l 0140 grid, that has been described earlier in the description of FIGS. 1 and 2.
  • Each of the larger size, lower frequency radiating elements is located at the intersections of another grid having the same cell form and size as that of the reference grid and displaced from the reference grid so that each lower frequency element 20 is located at a center of a cell of the reference grid.
  • the spacing between centers of the larger elements 20 is equal to the spacing between centers of the smaller elements 18, giving a spacing ratio of 1:1
  • the configuration provides for a range of beam scanning angles for the lower frequency radiation which is substantially larger than that for the higher frequency, as is sometimes required in radar search applications.
  • the smaller size, higher frequency radiating elements 18 are located at the intersections of the reference grid of equilateral triangles in the same manner as shown in FIGS. 1, 2, and 4.
  • the larger size, lower frequency radiating elements 20 are located at the intersections of a grid having equilateral triangular cells which are larger than those of the reference grid by a factor of the square root of3 and being offset from the reference grid, whereby every individual high frequency element 18 is abutting one, and only one, of the larger-size, lower frequency elements 20, thereby providing a spacing ratio of V721.
  • This spacing ratio also provides a larger scan angle capability at the lower frequency but not as large as that provided by the configuration of FIG. 4.
  • FIGS. 6 and 7 there is shown a perspective view of a portion of an interleaved antenna array which by way of example, shows a typical means for mounting the radiating elements in an alternative embodiment of the present invention, wherein the larger size, lower frequency radiating elements 84 are mounted coaxially with and behind an alternative form 86 of the smaller size, higher frequency radiating elements 18.
  • the higher frequency radiating element 86 does not contain the coil driver circuit and the electrical connecting pins 76 of radiating element 18, so that a simpler electrical connection can be made via a pair of coil leads 88A and 88B connecting directly to the phase shifter coil, not shown in FIGS. 6 and 7, of element 86.
  • the coil driver circuit, not shown, for radiating element 86 can be mounted beneath the lower frequency radiating element 84.
  • the smaller size, higher frequency elements 18 and 86 are located at the intersections of the reference grid, not shown.
  • the larger elements 84 are located along the reference grid lines at every second intersection, thereby providing a spacing ratio 2;l.
  • the diameters of all the radiating elements are approximately 0.3 wavelengths of the radiation which is transmitted by the radiating elements.
  • the spacing between centers of the higher frequency elements 86 and I8 is approximately one-half the free space wavelength of the radiation transmitted by these elements, and similarly, the spacing between centers of the lower frequency elements 84 is approximately onehalf the free space wavelength of the radiation transmitted by the lower frequency elements 84.
  • Each of the higher frequency coaxially mounted elements 86 is supported by four plastic struts 90, of a mounting bracket inserted in the oversized apertures of mounting plate 94.
  • Each of the lower frequency coaxially mounted elements 84 is supported by a metallic cylinder 92.
  • the struts are made from material which is essentially transparent to the radiation, and are used to support the high frequency elements 86 in coaxial relation with the lower frequency elements 84.
  • the struts 90 are affixed to the metallic mounting plate 94, as shown in the sectional view of FIG. 7, by mounting bolts 96 and strut flange 98.
  • the higher frequency radiating element 86 is connected to the struts 90 by means of bolts 30, and nuts 100 which are bonded to the underside of the struts 90.
  • the metallic cylinder 92 as shown in FIG.
  • the mounting plate 94 is affixed to the mounting plate 94 by mounting bolts 102 inserted through the upper cylinder mounting flange 104 and serves to direct the radiation from the lower frequency element 84 outwards through the opening 106 in the mounting plate 94.
  • the lower frequency element 84 is affixed by bolts, not shown, to the lower cylinder flange 108 of the metallic cylinder 92.
  • the two wire leads 88A and 88B extend through small holes in the metallic cartridge of element 86 and also through two holes, not shown, in metallic cylinder 92.
  • the leads are parallel and lie in a plane containing the axis of the radiating element 86, with a spacing between them of )t /4 where A, is the guide wavelength of the radiation transmitted by the lower frequency element 84.
  • the spacing of .,/4 has been selected to minimize reflections in the transmission of the lower frequency radiation through the metallic cylinder 92.
  • a phased array antenna including groups of electromagnetic radiating elements in which the radiating elements of one group having a radiation characteristic which is of a lower frequency and is circularly polarized are interleaved with the radiating elements of a second group having a radiation characteristic which is of a higher frequency and is circularly polarized in the opposite sense to the polarization of the radiation characteristic of the first group, at least one of said radiating elements of said first group having a radiating aperture having dimensions less than one-third wavelength of the radiation which is characteristic for that radiating element, at least one of said radiating elements of said first group having a matching structure to provide a radiation characteristic for said radiating element which is substantially equal to the radiation characteristic provided for a similar radiating element having an aperture with dimensions of one-half wavelength, the radiating elements in each of said groups being so located within the phased array antenna that the distance between centers of the radiating elements in any one group is substantially one-half wavelength of the radiation which is characteristic to that group.
  • a phased array antenna in which a first group of radiating elements which form a first beam of electromagnetic radiation at a first frequency are interleaved with a second group of radiating elements which form a second beam of electromagnetic radiation at a second frequency substantially equal to one-half the first frequency, individual elements of said first group of elements being located at a plurality of the intersections of a first grid formed by three sets of parallel lines which intersect to form grid cells each of which have the form of equilateral triangles a side of which is substantially equal to a half wavelength of said first radiation, the elements of said second group of elements being located at a plurality of the intersections of a second grid formed by three sets of parallel lines which intersect to form grid cells each of which have the form of equilateral triangles, a side of a grid cell of said second grid being parallel to and having a length equal to twice the length of a side of a grid cell of said first grid, an intersection of said second grid being located at the center of a grid cell of said first grid, whereby the range of scan angles
  • each of such radiating elements having a dielectrically loaded matching structure which provides a radiation characteristic which is substantially the same as the radiation characteristic provided by an aperture of dimensions substantially one-half wavelength of said free space radiation.
  • An antenna array comprising a plurality of groups of electromagnetic radiating elements in which the radiating elements of one group of said groups imparting a first phase characteristic to radiation transmitted from said one group are interleaved with radiating elements ofa second group of said groups of radiating elements, said radiating elements of said second group imparting a second phase characteristic to radiation transmitted from said second group, said second phase characteristic being variable with respect to said first phase characteristic, said radiating elements of said one group comprising a first cylindrical dielectric member and a second dielectric member coaxial to said first member for transmitting circularly polarized radiation, at least one of said radiating elements of said one group having a radiating aperture whose dimensions are less than approximately one-third wavelength of the radiation which is characteristic for that radiating element.
  • a phased array antenna comprising: a first set of electromagnetic radiating elements arranged for forming a first beam of radiation, the elements of said first set being so located within the phased array antenna that the distance between centers of these radiating elements is approximately one-half wavelength of radiation radiated by these elements;
  • a second set of electromagnetic radiating elements arranged for forming a second beam of radiation, the radiating elements of said second set being so located within the phased array antenna that the distance between centers of the radiating elements of said second set is approximately one-half wavelength of the radiation emitted by said elements of said second set, a radiating element of said second set of radiating elements being interleaved among the radiating elements of said first set of radiating elements such that a radiating element of said second set of radiating elements is positioned between radiating elements of said first set of radiating elements, the radiating elements of said second set being of physically smaller size than the radiating elements of said first set to permit said interleaving of said element of said second set among said elements of said first set; and
  • a phased array antenna comprising:
  • a first set of electromagnetic radiating elements arranged for forming a first beam of radiation
  • a second set of electromagnetic radiating elements arranged for forming a second beam of radiation, a radiating element of said second set of radiating elements being interleaved among the radiating elements of said first set of radiating elements such that a radiating element of said second set of radiating elements is positioned between radiating elements of said first set of radiating elements;
  • a plurality of the radiating elements of said first set comprising a first cylindrical dielectric member, a second dielectric member coaxial to said first dielectric member for coupling to circularly polarized radiation, and reflector means responsive to a preselected sense of circularly polarized l060l l 0142 radiation for reflecting radiant energy through said first and said second dielectric members.
  • An antenna array comprising:
  • the elements of a first group of said plurality of groups of radiating elements being arranged for forming a first electronically steerable beam of radiation;
  • the elements of a second group of said plurality of groups of radiating elements being arranged for forming a second electronically steerable beam of radiation, the radiating elements in said second group comprising means for making them insensitive to radiation having the frequency and the polarization of the radiation of the elements of said first group;
  • the distance between centers of the radiating elements in any one group of said groups of radiating elements being approximately one half wavelength of the radiation which is characteristic to that group;
  • An antenna array comprising:
  • At first group of said plurality of groups of radiating elements being arranged for forming a first electronically steerable beam of radiation
  • a second group of said plurality of groups of radiating elements being arranged for forming a second electronically steerable beam of radiation
  • the distance between centers of the radiating elements in any one group of said groups of radiating elements being approximately one-half wavelength of the radiation which is characteristic to that group;
  • the radiating elements in at least one group of said groups of electromagnetic radiating elements having radiating apertures having dimensions which are less than approximately onethird wavelength of the radiation which is characteristic for such radiating elements, and in which the dimensions of the radiating apertures of said antenna array equal approximately the dimensions of the radiating aperture formed by an antenna array of the radiating elements of at least one of the groups of said groups of electromagnetic radiating elements.
  • a phased array antenna comprising:
  • a first array of electromagnetic radiating elements emitting radiation having characteristics of a first frequency and a first polarization
  • a second array of electromagnetic radiating elements emitting radiation having the characteristics of a second frequency and a second polarization
  • the characteristics of frequency and polarization of the radiation of said first array being different from the characteristics of frequency and polarization of the radiation of said second array;
  • the distance between centers of the radiating elements in any one array of said arrays of radiating elements being approximately one-half wavelength of the radiation which is characteristic to that array;
  • a phased array antenna comprising:
  • a first array of electromagnetic radiating elements emitting radiation having characteristics of a first frequency and a first polarization
  • a second array of electromagnetic radiating elements emitting radiation having the characteristics of a second frequency and a second polarization, the elements of said second array comprising means for making these elements insensitive to radiation having the frequency and polarization of the radiation of elements of said first array;
  • phased array antenna as defined by claim 15 wherein said first array radiating elements have a radiation characteristic of a first frequency, and said second array radiating elements have a radiation characteristic of a second frequency.
  • a phased array antenna comprising:
  • a first array of electromagnetic radiating elements emitting radiation having characteristics of a first frequency and a first polarization
  • a second array of electromagnetic radiating elements emitting radiation having the characteristics of a second frequency in a second polarization
  • the characteristics of frequency and polarization of the radiation of said first array being different from the characteristics of frequency and polarization of the radiation of said second y means for varying the phase of radiation emitted by one element of this first array of electromagnetic radiating elements relative to another element of said first array to steer a beam of the radiation of said first array independently of the orientation of a beam of the radiation of said second array;
  • At least one of said first array radiating elements having a radiating aperture having dimensions less than approximately one-third wavelength of the radiation which is characteristic for that radiating element and having a matching structure to provide a radiation characteristic for that radiating element which is approximately equivalent to the radiation characteristic for a radiating element without said matching structure and having a radiating aperture whose dimensions are approximately one-half wavelength.

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Abstract

A phased array antenna including within its single electromagnetic radiating aperture two or more groups of radiating elements, each group of radiating elements being distinguished by the polarization and frequency spectrum of its radiation. The radiating elements of each group are of sufficiently small physical size compared to their free space wavelength to permit their being interleaved among the radiating elements of the other groups in a configuration whereby each group of radiating elements has approximately the same control of the beamwidth and the steering of its beam of radiation as would be the case if only one of these groups were present.

Description

Sttes ate t atelier et al.
MULTIPLE INTERLEAVED PHASE!) ANTENNA ARRAY PROVIDING SIMULTANEOUS OPERATION AT TWO FREQUENCIES AND TWO POLARIZATIONS lnventors: Burrell R. Hatcher, Bedford; Aldo R. Miccloli, Acton; Max C. Mohr,
Chelmsford; Edward J. Sheldon, Lexington, all of Mass.
Assignee: Raytheon Company, Lexington,
Mass.
Filed: Feb. 3, 1971 Appl. No.: 112,395
Related lJ.S. Application Data Continuation of Ser. No. 779,767, Nov. 29, 1968, abandoned.
US. Cl ..343/754, 333/31 R, 343/778, 343/854 Int. Cl. ..l'l0lq 19/08 Field of Search ..343/725, 754, 771, 776-779, 343/853, 854
3,259,902 7/1966 Malech ..343/777 X 3,480,958 11/1969 Tcheditch ..343/854 X 3,243,818 3/1966 l'loltzman ..343/77l 3,267,477 8/1966 Brickey ..343/779 X 3,281,851 10/1966 Goebels, Jr.... ....343/77l X 3,482,248 12/1969 Jones, Jr ....343/771 X 3,500,422 3/1970 Cheston et a1 ..343/778 3,518,695 6/1970 Schroeder .343/854 3,553,706 1/1971 Charlton ..343/853 Primary Examiner-Paul L. Gensler Attorney-Harold A. Murphy, Joseph D. Pannone and Herbert W. Arnold [57] ABSTRACT A phased array antenna including within its single electromagnetic radiating aperture two or more groups of radiating elements, each group of radiating elements being distinguished by the polarization and frequency spectrum of its radiation. The radiating elements of each group are of sufficiently small physical size compared to their free space wavelength to permit their being interleaved among the radiating elements of the other groups in a configuration whereby each group of radiating elements has approximately the same control of the beamwidth and the steering of its beam of radiation as would be the case if only one of these groups were present.
19 Claims, 7 Drawing Figures PMENMBHEB 1 I 72 3. 706, 998
sum 1 BF 3 INVENTORS BURRELL R. HATCHER ALDO R. M/GG/OL/ MAX 6. MOHR EDWARD J SHELDON Y 71 W /M ATTORNEY PATENTED E R 9 @972 3,706,998
SHEET 2 BF 3 I/VVENTORS BURRELL RHATGHER ALDO R. M/GC/OL/ MAX 6 MOHR EDWARD J. SHELDON ATTORNEY PATENFEE m 19 m2 SHEET 3 BF 3 //V VE IV 7' 0/?8 HA TCHER BURRELL R ALDO R. M/CC/OL/ MAX 0. MOHR EDWARD .1. SHELDON By /c [a I ZK fl ATTORNEY MULTIPLE INTERLEAVED PHASED ANTENNA ARRAY PROVIDING SIMULTANEOUS OPERATION AT TWO FREQUENCIES AND TWO POLARIZATIONS This application is a continuation of application Ser. No. 779,767, filed on Nov. 29, 1968, now abandoned.
BACKGROUND OF THE INVENTION This invention relates to antennas having a plurality of electromagnetic radiating elements, and more particularly, to the utilization ofa single radiating aperture having elements of differing characteristics to provide a capability to operate simultaneously at more than one frequency band, polarization state and scan sector or any combination of these three.
An installation employing two or more phased array antennas is required for certain applications as in the situation where signals of differing carrier frequencies or polarizations are required to be transmitted to a single target vehicle. Such installations typically require a number of support structures for the individual phased array antennas which entail considerable weight, space, and auxiliary equipment.
It is therefore desirable to provide an antenna having a single electromagnetic radiating aperture which combines the features of a plurality of individual antenna arrays. These features include, for example, a frequency diversity capability and a capability to transmit in the various frequency bands and in the polarizations of the individual arrays as well as means for steering each of the plurality of beams of radiation. This aperture need be no larger than the apertures of the largest individual antenna since each beam of radiation is generated independently of the other beams and therefore the aperture dimensions of the individual array are adequate to form the beam. A single aperture antenna of this sort is particularly advantageous for mobile applications, for example, where a phased array radar is to be mounted on a space vehicle or aircraft. In addition to the savings in space, weight, and expense, this antenna also provides a common axis for the plurality of beams of radiation.
In order for an antenna having a single aperture to generate simultaneously the beams of electromagnetic radiation which are characteristic of each of a plurality of individual antenna arrays and more particularly, of a plurality of individual phased array antennas in which the phases of radiation of the individual radiating elements are varied with respect to one another to provide beam steering or scanning, it is frequently required to have the means to simultaneously transmit at different frequencies and polarizations and to generate a plurality of beams of radiation such that each beam is steered independently of the other beams. These requirements are met by the use of a plurality of radiating elements which have the characteristics of the radiating elements of the individual array. However, an important problem arises relating to physically locating these elements within a single aperture, since within a conventional array having a single type of radiating element all such radiating elements are typically contiguous without spaces between them large enough to accommodate similar radiating elements. Also, the interelement spacing, that is, the distance between centers of the radiating elements of an individual array cannot be increased to provide spaces for other radiating elements, because the interelement spacing plays a critical role in forming the beam of radiation. For example, an increase in the interelement spacing alters the beamwidth and such increase can be great enough to produce grating nulls in the antenna directivity pattern, particularly at large scanning angles. It is, therefore, desirable to provide an improved antenna array comprising electromagnetic radiating elements with radiation characteristics similar to those of two or more individual arrays, and having an antenna radiating aperture whose physical size is no larger than the radiating aperture of the largest of the individual arrays.
It is an object of the present invention to provide a novel antenna array which generates beams of radiation having approximately the same beamwidths, polarization, and frequency spectrums as the beams of radiation generated by a plurality of individual arrays, yet has a physical structure which weighs less, and is more economical to construct than the total of the plurality of structures of the individual arrays.
It is also an object of the present invention to provide an improved phased array antenna which transmits simultaneously at two frequencies and generates two beams of radiation one at each frequency such that the two beams can be coaxial.
SUMMARY OF THE INVENTION In accordance with the invention, an antenna array is constructed of electromagnetic radiating elements drawn from two or more individual arrays of radiating elements wherein each of said individual arrays is identified by the characteristics of directivity pattern, polarization, and frequency spectrum of the beam of radiations which it generates. A group of electromagnetic radiating elements drawn from each of said individual arrays are dielectrically loaded to be of sufficiently small physical size compared to their free space wavelengths to permit their being interleaved among the radiating elements drawn from each of the other individual arrays, and the configuration and spacing of the interleaved radiating elements is such that the above characteristics of the individual arrays are retained. In the interleaved antenna array, the interelement spacing, namely, the spacing between centers of the radiating elements drawn from any one group, is typically approximately one-half the free space wavelength of the radiation generated by these elements. Accordingly, each radiating element of each of said groups is constructed with a physical size which is smaller than the interelement spacing to permit the radiating elements to be spaced in said array with the aforementioned one-half free space wavelength spacing between centers.
In the case of an antenna array which is formed by interleaving two groups of electromagnetic radiating elements, it is preferable that the polarization of the radiation which is characteristic to the radiating elements of one group be orthogonal to the polarization of the radiation which is characteristic to the radiating elements of the second group in order to minimize a cross coupling between the two groups of radiating elements. With this arrangement, a beam of radiation generated by the radiating elements of one group as, for example, with a phased array antenna, can be scanned continulOGOll 0137 ously through a sector of space approximately independently of the beam of radiation generated by the radiating elements of the second group.
BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned objects and other features of the invention are explained in the following description taken in connection with the accompanying drawings wherein:
FIG. 1 is an isometric view of one embodiment of this invention having a reflector-type optically fed antenna array, the antenna array having electromagnetic radiat' ing elements of two different frequencies, said elements being interleaved so that the spacing between centers of the lower frequency radiating elements is equal to twice the spacing between centers of the higher frequency radiating elements;
FIG. 2 is an enlarged fragmentary isometric view of the antenna array taken along the line 2-2 of FIG. 1;
FIG. 3 is an isometric view, partially cutaway, of one embodiment of a radiating element of the array of FIG. 1 wherein the radiating aperture has a diameter which is approximately 0.2 wavelengths of the radiation transmitted by this radiating element;
FIG. 4 is a fragmentary perspective view of a portion of an alternative embodiment of the interleaved array of FIG. 1 wherein the spacing between centers of the lower frequency radiating elements is equal to the spacing between centers of the higher frequency radiating elements;
FIG. 5 is an enlarged fragmentary perspective view of a portion of an alternative embodiment of the interleaved antenna array of FIG. 1 wherein the spacing between centers of the lower frequency radiating elements is greater by a factor of 3 than the spacing between centers of the higher frequency radiating elements;
FIG. 6 is an enlarged fragmentary perspective view of a portion of an alternative embodiment of the interleaved antenna array of FIG. 1 wherein the spacing between centers of the lower frequency radiating elements is equal to twice the spacing between centers of the higher frequency radiating elements, and wherein a lower frequency radiating element is mounted beneath and coaxial with a higher frequency radiating element; and
FIG. 7 is a fragmentary view, partially in section, ofa higher frequency coaxially mounted radiating element and its mounting strut.
DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. I, there is shown a phased array antenna 10 which includes an interleaved antenna array 12 which serves as a reflecting surface for directing electromagnetic radiation to the feed horns l4 and 16 for receiving said radiation, and during transmission, for collimating the radiation from the feed horns 14 and 16 to form individual beams of radiation. The phased array antenna 10 is adapted to operate in a novel manner simultaneously with radiation at two frequencies and two polarizations. The higher frequency radiation has a circular polarization of one sense, that is, clockwise or counterclockwise and is reflected from the smaller radiating elements 18, two of these elements being designated 18A and 18B. The lower frequency radiation has a circular polarization of the opposite sense in order to minimize cross-coupling between the higher and lower frequency radiating elements and is reflected from the larger radiating elements 20, one of which is designated 20A. In transmitting electromagnetic radiation, the antenna 10 operates in the manner of phased array antennas where each group of radiating elements 18 and 20 imparts a phase shift to radiation emanating from the high frequency born 14 and the low frequency horn 16 to direct it in the desired direction. In receiving electromagnetic energy, the radiating elements 18 and 20 direct the received radiation which is incident upon the face of array 12 in the directions respectively of the feed horns 14 and 16. The amount of the phase shift is controlled by computer-generated signals, not shown, applied to each of the, radiating elements. The feed horns 14 and 16, as shown, are of different physical dimensions to accommodate the two frequencies, the horn 14 having a smaller cross section to operate at the higher frequency and the born 16 having a larger cross section to operate at the lower frequency. Electromagnetic energy from each horn illuminates the entire face of the array.
The antenna 10 is provided with a support structure comprising a metallic mounting plate 22 and supporting struts 24. The metallic mounting plate 22 also serves as a ground plane for the radiation, and can be hexagonal, as shown, or of any convenient form, such as circular or square, and is provided with apertures to receive the radiating elements 18 and 20, and hold these elements 18 and 20 spaced in a manner to be described. The struts 24 support the mounting plate 22 and also support transmitting and receiving equipment contained in metallic cabinet 26. The feed horns 14 and 16 are connected to the transmitting and receiving equipment and extend outwardly from the electronics cabinet 26. The feed horns are rigidly attached to the mounting plate 22 by means of a bracket 28. As shown in FIG. I, the higher and lower frequency radiating elements 18 and 20 are uniformly distributed throughout the interleaved array 12 so that the high and low frequency beams of radiation generated by the antenna 10 are coaxial.
The arrangement and means for mounting the radiating elements 18 and 20 are shown in FIG. I and in greater detail in the enlarged fragmentary view of FIG. 2. The radiating elements 18 and 20 are arranged in a configuration, as' seen in FIG. 2, in which each of the larger size, lower frequency elements 20 abuts three smaller-size, higher frequency elements 18 located in equally spaced-apart relation around the periphery of said larger element 20. Thereby lines, now shown, connecting the three elements form an equilateral triangle or cell. The smaller size, higher frequency elements 13 are located with respect to each other at the intersections of three sets of parallel lines, not shown, which form a grid having cells, each of which is in the form and size of said equilateral triangle. The spacing between the centers of the higher frequency radiating elements 18 is approximately one-half wavelength of the radiation which is transmitted by the radiating element 18. The higher frequency is, by way of example, equal to twice the lower frequency and therefore the lower frequency radiating elements 20 are shown with I060l l 0138 a diameter that is twice as large as the diameter of the higher frequency elements 18. The lower frequency elements are similarly positioned at the intersections of three sets of parallel lines, not shown, which form another grid having equilateral triangular cells whose sides are twice as long as those of the aforementioned grid for the higher frequency elements 18, so that the spacing between centers of the lower frequency elements 20 is twice as large as the spacing between centers of the higher frequency elements 18. It is convenient to define a spacing ratio which is the ratio of the spacing between centers of the larger size, lower frequency elements 20 to the spacing between centers of the smaller size, higher frequency elements 18. In the embodiment of FIG. 1 and FIG. 2 the spacing ratio is 2:1, so that the high and low frequency beams of radiation can be steered over approximately the same range of beam steering angles that do not introduce grating nulls.
The radiating elements 18 and 20 are affixed with their axes perpendicular to the mounting plate 22 by mounting bolts 30, one of which is designated 30A. The bolts 30 are tightened against the lips 32 of recessed portions 34 of a higher frequency radiating elements mounting flange 36 and are similarly tightened against the lips 38 of recessed portions 40 of a lower frequency radiating elements mounting flange 42. The lips 32 and 38 and the recessed portions 34 and 40 have dimensions which permit a single mounting bolt, such as bolt 30A, to be utilized at the point of proximity between two abutting radiating elements such as the elements 18A and 20A. In the configuration of FIG. 1 and FIG. 2, there are also higher frequency elements which do not abut a low frequency element, such as the higher frequency element 18B. Each of the higher frequency elements 18 are spaced in the aforementioned configuration to be equidistant from each neighboring high frequency element. In FIG. 2, there is also shown a cartridge or case 44 and matching structure 46 for each higher frequency element, and a cartridge or case 48 and matching structure 50 for each lower frequency element which are described below.
Referring to FIG. 3, there is shown a detailed isometric view, partially cut away, of an individual high frequency radiating element 18. This description is also applicable to a low frequency element 20, since the two elements have similar structures, the essential difference being in their relative sizes. The radiating element 18 is encased in a metallic cylindrical cartridge 44, preferably of Mu-metal, which serves as a magnetic shield and as a support structure for the components of the radiating element. The diameter of the radiating element is approximately 0.2 wavelengths of the freespace radiation which is transmitted by this radiating element. This diameter is substantially smaller than the diameter of approximately one-half wavelength customarily employed for cylindrical elements in phased array antennas. Because of this reduced diameter and the corresponding reduction in size of the radiating apertures of the individual radiating elements 18 and 20 of the present invention, the front ends of these elements are equipped, as shown in FIG. 3, with a dielectrically loaded cylindrical waveguide 52 and matching structure 46 which provide effective radiation from these smaller radiating apertures.
At the front end of the radiating element 18 the matching structure 46 has the form of a cylindrical tubular segment or annulus of a ceramic material, such as for example alumina, to provide for radiation from a small aperture, in a well-known manner, by generating higher order waveguide modes. This type of matching structure is particularly adapted to receive radiation over a range of scan angles which is characteristic of phased array antenna operation. Electromagnetic radiation propagates within the ceramic material of the matching structure 46 at a slower speed than in air. Due to the slower speed of propagation, the relatively small dimensions of the ceramic matching structure 46 are sufficiently large to support a number of waveguide modes which include the dominant mode and higher order modes. The guide wavelengths of these modes depend on the scan angle, polarization and frequency of the radiation transmitted by the antenna array 12. In order to support approximately five propagating modes which transmit most of the radiated power, the matching structure 46 is typically constructed so that the difference between its inner and outer radius is equal approximately to two wavelengths of the radiation transmitted in a medium of this type of ceramic material; and the axial length of the matching structure 46 is typically four wavelengths of the radiation which is transmitted in a medium of this type of ceramic material. The matching structure 46 is reciprocal so that multiple modes are generated both with incident and transmitted radiation. The combination of the dominant plus the higher order modes of radiation provide for a radiation efficiency and bandwidth from a small aperture, such as the present radiating aperture having a diameter of approximately 0.2 wavelengths of the free space radiation, which approximates that of a radiator transmitting in the dominant mode from an aperture having a diameter of approximately 0.5 wavelengths of the free-space radiation. Upon receiving radiation, the matching structure 46 provides the aforementioned modes, and with the aid of the dielectrically loaded cylindrical waveguide 52 and a wellknown impedance transformer 54 which give differential phase velocities to these waveguide modes, the plurality of these waveguide modes are combined to produce a single circular waveguide mode, the TE mode at the junction of transformer 54 and phase shifter 56. This mode is desirable since it facilitates operation of the phase shifter 56. The circular waveguide 52 also compensate for the mutual coupling between the individual radiating elements which transmit radiation of the same frequency, so that each of these radiating elements can impart the desired phase shift to the radiation essentially independently of the phase shift being imparted by the other elements.
The section of circular waveguide 52 is adjacent the matching structure 46 and is dielectrically loaded with materials having different dielectric constants in order to impart the aforementioned differential phase velocities to the various waveguide modes. While several different dielectric materials can be used, it has been found by experimentation that the use of two dielectric materials, quartz and ceramic for example, is sufficient to provide the differential phase velocities. Ac cordingly, a quartz rod 58 is disposed along the axis of the waveguide 52 and is mounted within a ceramic l060l l 0139 cylinder 60, the dimensions of which will be described. The ceramic cylinder 60 is supported by the metallic case 44 which also serves as the waveguide wall. The use of the two different dielectrics results in a nonlinearity in the differences between the phase velocities of the various waveguide modes whereby the several wavefronts of each of these modes from the matching structure 46 advance along the waveguide 52 to reach the terminus of the waveguide 52 with a small difference in their respective phases. The difference in the phases of their respective wavefronts is further reduced in the impedance transformer 54 so that a single wavefront, that of the TE mode, is launched into the phase shifter 56. In order to combine the wavefronts of approximately five waveguide modes, the difference between the outer and inner radii of the ceramic dielectric cylinder 60 is typically one wavelength of the radiation transmitted in a medium of this ceramic material; the radius of the quartz dielectric rod 58 is typically two wavelengths of the radiation transmitted in a medium of this quartz material; and the axial length of the circular waveguide 52 is typically eight wavelengths of the radiation which is transmitted in a medium of this quartz material.
The impedance transformer 54 which is positioned between the dielectrically loaded waveguide 52 and the phase shifter 56 is in the form of an annulus of dielectric material, preferably of ceramic, supported within a metallic support 62. In combination, the ceramic annulus of the impedance transformer 54 and the metallic support 62 act as a short section of circular waveguide which launches the TE mode into the phase shifter 56. In order to combine the wavefronts of approximately five waveguide modes, the difference between the outer and inner radii of the ceramic annulus of the impedance transformer 54 is typically four wavelengths of the radiation which is transmitted in a medium of this ceramic material; and the axial length of the impedance transformer is typically one and one-half wavelengths of the radiation, which is transmitted in a medium of this ceramic material.
The compensation for the mutual coupling between radiating elements transmitting at like frequencies of radiation is effected by virtue of the fact that the combination of matching structure, dielectrically loaded waveguide, and impedance transformer matches the higher order waveguide modes induced by radiation incident upon the antenna array over the usual range of scanning angles typical of phased array operation. Accordingly, waveguide modes induced by radiation from adjacent elements are essentially not propagated through the dielectrically loaded waveguide and impedance transformer to the phase shifter. The construction of the radiating element shown herein provides a relatively broad bandwidth in excess of approximately 8 percent.
In the embodiment of FIG. 1, each of the radiating elements 18 and 20 provides the dual function of reflecting and imparting a phase shift to the incident radiation. Accordingly, the radiating element 18, as shown in FIG. 3, contains phase shifter 56 terminated by a short-circuit in the form of a metallic cap or disk 64 which reflects the radiation. The phase shifter 56 has essentially the same form as that disclosed in the patents to Francis J. OHara and Howard Scharfman,
US. Pat. No. 3,058,049 which issued Oct. 9, 1962 and U.S. Pat. No. 3,100,287, which issued Aug. 6, I963. The phase shifter 56 comprises a waveguide structure having a dielectric cylinder 66 enclosing an inner core in the form of a ferrite rod 68, a metallic conducting cylindrical wall 70 typically formed by depositing silver on the outer surface of the dielectric cylinder 66, and a control coil 72, coaxially mounted with the ferrite rod 68 and enclosing the cylindrical wall 70, which controls the magnetic state of the ferrite rod 68. This type of phase shifter responds to a circularly polarized wave of one sense only, and thereby minimizes cross-coupling between radiating elements which respond to circular polarization of the opposite sense. The control coil 72 is connected via a pair of leads 74 to a coil driver circuit, not shown, of a standard well-known form, which is energized through pins 76 in the back end of the radiating element 18 in a well-known manner to provide the amount of phase shift required for a desired beam scanning. The cylindrical wall 70 of the phase shifter 56 is supported at its front end by a portion of the metallic support 62 and at its back end by an axial extension 78 of the short-circuit cap or disk 64.
In operation therefore, computer generated signals, not shown, are applied to the pins of the radiating elements to energize the coil driver circuit, not shown. In each radiating element the coil driver circuit supplies current to the controlcoil to provide the magnetic field in the ferrite rod which, in turn imparts a phase shift between the incident and reflected radiation. The high frequency elements and the low frequency elements of FIG. 1 receive separate sets of computer generated drive signals so that high and low frequency beams of radiation can be directed independently of each other. The matching structure, the dielectrically loaded cylindrical waveguide, and the impedance transformer function in combination as a unit which provides a broadband impedance match from the radiating aperture at the matching structure to the phase shifter, and also compensates for mutual coupling among adjacent radiating elements.
Referring now to FIGS. 4 and 5, there are shown two alternative embodiments of the present invention in which the radiating elements 18 and 20 are interleaved in alternative configurations. These configurations provide a spacing between centers of the higher frequency radiating elements 18 which is less than or approximately equal to one-half the free space wavelength of the radiation transmitted by element 18, and a spacing between centers of the lower frequency radiating elements 20 which is less than or equal to one-half the free space wavelength of the radiation transmitted by element 20. The diameter of each radiating element in FIGS. 4 and 5 is approximately 0.2 wavelengths of the free space radiation transmitted by that radiating ele ment. In both figures there is shown a perspective view of a portion of an interleaved antenna array wherein the radiating elements 18 and 20 are affixed to a mounting plate by bolts 30 in contact with the mounting flanges 36 and 42, said mounting plate being designated by 80 in FIG. 4 and by 82 in FIG. 5.
In the embodiment of FIG. 4, the smaller size higher frequency radiating elements 18 are located at the in tersections of a grid of equilateral triangles, not shown, the same grid, hereinafter designated the reference I060l l 0140 grid, that has been described earlier in the description of FIGS. 1 and 2. Each of the larger size, lower frequency radiating elements is located at the intersections of another grid having the same cell form and size as that of the reference grid and displaced from the reference grid so that each lower frequency element 20 is located at a center of a cell of the reference grid. Thus, the spacing between centers of the larger elements 20 is equal to the spacing between centers of the smaller elements 18, giving a spacing ratio of 1:1 Thus, in the situation where the higher frequency is equal to twice the lower frequency, the configuration provides for a range of beam scanning angles for the lower frequency radiation which is substantially larger than that for the higher frequency, as is sometimes required in radar search applications.
In FIG. 5, the smaller size, higher frequency radiating elements 18 are located at the intersections of the reference grid of equilateral triangles in the same manner as shown in FIGS. 1, 2, and 4. The larger size, lower frequency radiating elements 20 are located at the intersections of a grid having equilateral triangular cells which are larger than those of the reference grid by a factor of the square root of3 and being offset from the reference grid, whereby every individual high frequency element 18 is abutting one, and only one, of the larger-size, lower frequency elements 20, thereby providing a spacing ratio of V721. This spacing ratio also provides a larger scan angle capability at the lower frequency but not as large as that provided by the configuration of FIG. 4.
Referring now to FIGS. 6 and 7, there is shown a perspective view of a portion of an interleaved antenna array which by way of example, shows a typical means for mounting the radiating elements in an alternative embodiment of the present invention, wherein the larger size, lower frequency radiating elements 84 are mounted coaxially with and behind an alternative form 86 of the smaller size, higher frequency radiating elements 18. The higher frequency radiating element 86, as modified, does not contain the coil driver circuit and the electrical connecting pins 76 of radiating element 18, so that a simpler electrical connection can be made via a pair of coil leads 88A and 88B connecting directly to the phase shifter coil, not shown in FIGS. 6 and 7, of element 86. The coil driver circuit, not shown, for radiating element 86 can be mounted beneath the lower frequency radiating element 84. The smaller size, higher frequency elements 18 and 86 are located at the intersections of the reference grid, not shown. The larger elements 84 are located along the reference grid lines at every second intersection, thereby providing a spacing ratio 2;l.
The diameters of all the radiating elements are approximately 0.3 wavelengths of the radiation which is transmitted by the radiating elements. The spacing between centers of the higher frequency elements 86 and I8 is approximately one-half the free space wavelength of the radiation transmitted by these elements, and similarly, the spacing between centers of the lower frequency elements 84 is approximately onehalf the free space wavelength of the radiation transmitted by the lower frequency elements 84. Each of the higher frequency coaxially mounted elements 86 is supported by four plastic struts 90, of a mounting bracket inserted in the oversized apertures of mounting plate 94. Each of the lower frequency coaxially mounted elements 84 is supported by a metallic cylinder 92. The struts are made from material which is essentially transparent to the radiation, and are used to support the high frequency elements 86 in coaxial relation with the lower frequency elements 84. The struts 90 are affixed to the metallic mounting plate 94, as shown in the sectional view of FIG. 7, by mounting bolts 96 and strut flange 98. The higher frequency radiating element 86 is connected to the struts 90 by means of bolts 30, and nuts 100 which are bonded to the underside of the struts 90. The metallic cylinder 92, as shown in FIG. 6, is affixed to the mounting plate 94 by mounting bolts 102 inserted through the upper cylinder mounting flange 104 and serves to direct the radiation from the lower frequency element 84 outwards through the opening 106 in the mounting plate 94. The lower frequency element 84 is affixed by bolts, not shown, to the lower cylinder flange 108 of the metallic cylinder 92. The two wire leads 88A and 88B extend through small holes in the metallic cartridge of element 86 and also through two holes, not shown, in metallic cylinder 92. The leads are parallel and lie in a plane containing the axis of the radiating element 86, with a spacing between them of )t /4 where A, is the guide wavelength of the radiation transmitted by the lower frequency element 84. The spacing of .,/4 has been selected to minimize reflections in the transmission of the lower frequency radiation through the metallic cylinder 92.
It is understood that the above-described embodiments of the invention are illustrative only, and modifications thereof will occur to those skilled in the art. For example, three or more different types of radiating elements differing in polarization and in frequency can be interleaved in a phased array antenna; other phased array antenna configurations with spacing ratios such as 2, 3 and 4 can be utilized; other forms of matching structures for the radiating elements such as a ceramic annulus mounted at the front end of the radiating element within the waveguide segment can be utilized; other forms of electromagnetic radiating elements such as dipoles having a loading structure for effective radiation can be interleaved in such electronically beam steered phased array antennas; three or more radiating elements can be mounted coaxially in the interleaved array and the antenna type of feed can be of other forms such as the cassegrain, and a lens type of phased array antenna in which the feed horns are located behind the interleaved antenna array can be used. Accordingly, it is desired that this invention is not to be limited to the embodiments disclosed herein but is to be limited only as defined by the appended claims.
We claim:
1. A phased array antenna including groups of electromagnetic radiating elements in which the radiating elements of one group having a radiation characteristic which is of a lower frequency and is circularly polarized are interleaved with the radiating elements of a second group having a radiation characteristic which is of a higher frequency and is circularly polarized in the opposite sense to the polarization of the radiation characteristic of the first group, at least one of said radiating elements of said first group having a radiating aperture having dimensions less than one-third wavelength of the radiation which is characteristic for that radiating element, at least one of said radiating elements of said first group having a matching structure to provide a radiation characteristic for said radiating element which is substantially equal to the radiation characteristic provided for a similar radiating element having an aperture with dimensions of one-half wavelength, the radiating elements in each of said groups being so located within the phased array antenna that the distance between centers of the radiating elements in any one group is substantially one-half wavelength of the radiation which is characteristic to that group.
2. The system of claim 1 in which the radiating elements in at least one of each of said groups have a cylindrical form.
3. The system of claim 1 in which a plurality of the radiating elements drawn from a plurality of said groups are coaxially mounted with respect to each other.
4. A phased array antenna in which a first group of radiating elements which form a first beam of electromagnetic radiation at a first frequency are interleaved with a second group of radiating elements which form a second beam of electromagnetic radiation at a second frequency substantially equal to one-half the first frequency, individual elements of said first group of elements being located at a plurality of the intersections of a first grid formed by three sets of parallel lines which intersect to form grid cells each of which have the form of equilateral triangles a side of which is substantially equal to a half wavelength of said first radiation, the elements of said second group of elements being located at a plurality of the intersections of a second grid formed by three sets of parallel lines which intersect to form grid cells each of which have the form of equilateral triangles, a side of a grid cell of said second grid being parallel to and having a length equal to twice the length of a side of a grid cell of said first grid, an intersection of said second grid being located at the center of a grid cell of said first grid, whereby the range of scan angles of said first beam of radiation is substantially equal to the range of scan angles of said second beam of radiation.
5. The system of claim 4 in which individual radiating elements of said groups have radiating apertures whose dimensions are substantially less than one-third wavelength of the free space radiation transmitted and received by such radiating elements. each of such radiating elements having a dielectrically loaded matching structure which provides a radiation characteristic which is substantially the same as the radiation characteristic provided by an aperture of dimensions substantially one-half wavelength of said free space radiation.
6. An antenna array comprising a plurality of groups of electromagnetic radiating elements in which the radiating elements of one group of said groups imparting a first phase characteristic to radiation transmitted from said one group are interleaved with radiating elements ofa second group of said groups of radiating elements, said radiating elements of said second group imparting a second phase characteristic to radiation transmitted from said second group, said second phase characteristic being variable with respect to said first phase characteristic, said radiating elements of said one group comprising a first cylindrical dielectric member and a second dielectric member coaxial to said first member for transmitting circularly polarized radiation, at least one of said radiating elements of said one group having a radiating aperture whose dimensions are less than approximately one-third wavelength of the radiation which is characteristic for that radiating element.
7. A phased array antenna comprising: a first set of electromagnetic radiating elements arranged for forming a first beam of radiation, the elements of said first set being so located within the phased array antenna that the distance between centers of these radiating elements is approximately one-half wavelength of radiation radiated by these elements;
a second set of electromagnetic radiating elements arranged for forming a second beam of radiation, the radiating elements of said second set being so located within the phased array antenna that the distance between centers of the radiating elements of said second set is approximately one-half wavelength of the radiation emitted by said elements of said second set, a radiating element of said second set of radiating elements being interleaved among the radiating elements of said first set of radiating elements such that a radiating element of said second set of radiating elements is positioned between radiating elements of said first set of radiating elements, the radiating elements of said second set being of physically smaller size than the radiating elements of said first set to permit said interleaving of said element of said second set among said elements of said first set; and
means for varying the phase independently of the frequency of radiation emitted by a radiating ele ment of said first set of radiating elements with respect to the phase of radiation emitted by another radiating element of said first set of radiating elements to permit a variation in the orientation of said first beam of radiation relative to an orientation of said second beam of radiation.
8. A phased array antenna comprising:
a first set of electromagnetic radiating elements arranged for forming a first beam of radiation;
a second set of electromagnetic radiating elements arranged for forming a second beam of radiation, a radiating element of said second set of radiating elements being interleaved among the radiating elements of said first set of radiating elements such that a radiating element of said second set of radiating elements is positioned between radiating elements of said first set of radiating elements;
means for varying the phase independently of the frequency of radiation emitted by a radiating element of said first set of radiating elements with respect to the phase of radiation emitted by another radiating element of said first set of radiating elements to permit a variation in the orientation of said first beam of radiation relative to an orientation of said second beam of radiation; and
a plurality of the radiating elements of said first set comprising a first cylindrical dielectric member, a second dielectric member coaxial to said first dielectric member for coupling to circularly polarized radiation, and reflector means responsive to a preselected sense of circularly polarized l060l l 0142 radiation for reflecting radiant energy through said first and said second dielectric members.
9. An antenna array comprising:
a plurality of groups of electromagnetic radiating elements;
the elements of a first group of said plurality of groups of radiating elements being arranged for forming a first electronically steerable beam of radiation;
the elements of a second group of said plurality of groups of radiating elements being arranged for forming a second electronically steerable beam of radiation, the radiating elements in said second group comprising means for making them insensitive to radiation having the frequency and the polarization of the radiation of the elements of said first group;
means for positioning individual elements of said second group of radiating elements among elements of said first group of radiating elements for interleaving said second group of radiating elements with said first group of radiating elements;
the distance between centers of the radiating elements in any one group of said groups of radiating elements being approximately one half wavelength of the radiation which is characteristic to that group;
means for varying the phase independently of the frequency of radiation of one of said elements of said first group of radiating elements with respect to another element of said first group of radiating elements; and
means for varying the phase of radiation of one element of said second group of radiating elements with respect to another element of said second group of radiating elements independently of the phases of said first group of radiating elements for independently steering a plurality of beams of radiation relative to said antenna array.
10. An antenna array comprising:
a plurality of groups of electromagnetic radiating elements;
at first group of said plurality of groups of radiating elements being arranged for forming a first electronically steerable beam of radiation;
a second group of said plurality of groups of radiating elements being arranged for forming a second electronically steerable beam of radiation;
means for positioning individual elements of said second group of radiating elements among elements of said first group of radiating elements for interleaving said second group of radiating elements with said first group of radiating elements;
means for varying the phase independently of the frequency of radiation of one of said elements of said first group of radiating elements with respect to another element of said first group of said radiating elements;
means for varying the phase of radiation of one element of said second group of radiating elements with respect to another element of said second group of radiating elements independently of the phases of said first group of radiating elements for independently steering a plurality of beams of radiation relative to said antenna array;
the distance between centers of the radiating elements in any one group of said groups of radiating elements being approximately one-half wavelength of the radiation which is characteristic to that group; and
the radiating elements in at least one group of said groups of electromagnetic radiating elements having radiating apertures having dimensions which are less than approximately onethird wavelength of the radiation which is characteristic for such radiating elements, and in which the dimensions of the radiating apertures of said antenna array equal approximately the dimensions of the radiating aperture formed by an antenna array of the radiating elements of at least one of the groups of said groups of electromagnetic radiating elements.
11. A phased array antenna comprising:
a first array of electromagnetic radiating elements emitting radiation having characteristics of a first frequency and a first polarization;
a second array of electromagnetic radiating elements emitting radiation having the characteristics of a second frequency and a second polarization;
means for positioning the radiating elements of said second array of electromagnetic radiating elements within cells of a grid composed of lines interconnecting the radiating elements of said first array of electromagnetic radiating elements;
at least one of the characteristics of frequency and polarization of the radiation of said first array being different from the characteristics of frequency and polarization of the radiation of said second array;
the distance between centers of the radiating elements in any one array of said arrays of radiating elements being approximately one-half wavelength of the radiation which is characteristic to that array;
means for varying the frequency of radiation of said first array independently of the frequency of radiation of said second array; and
means for varying the phase independently of the frequency of radiation emitted by one element of said first array of electromagnetic radiating elements relative to another element of said first array to permit steering ofa beam of the radiation of said first array relative to a beam of the radiation of said second array.
12. The system as defined by claim 11 including means for steering a beam of radiation formed by the radiating elements of said first array independently of a beam of radiation formed by the radiating elements of said second array.
13. The system as defined by claim 12 in which the radiating elements of said first array are spaced with reference to the radiating elements of said second array in a configuration which provides a range of scan angles of said beam of radiation formed by radiating elements of said first array which is substantially the same as the range of scan angles of the beam of radiation formed by the radiating elements of said second array.
14. The system as defined by claim 12 in which the radiating elements of said first array are spaced with reference to the radiating elements of said second array to provide a range of scan angles in the radiation pattern of the radiating elements of said first array which is substantially the same as the range of scan angles in the radiation pattern of radiating elements of said second array.
15. A phased array antenna comprising:
a first array of electromagnetic radiating elements emitting radiation having characteristics of a first frequency and a first polarization;
a second array of electromagnetic radiating elements emitting radiation having the characteristics of a second frequency and a second polarization, the elements of said second array comprising means for making these elements insensitive to radiation having the frequency and polarization of the radiation of elements of said first array;
means for interleaving the radiating elements of said second array of electromagnetic radiating elements among the radiating elements of said first array of electromagnetic radiating elements; the distance between centers of the radiating elements in any one array of said arrays of radiating elements being approximately one-half wavelength of the radiation which is characteristic to that array;
at least one of the characteristics of frequency and polarization of the radiation of said first array being different from the characteristics of frequency and polarization of the radiation of said second array; and
means for varying the phase of radiation emitted by one element of said first array of electromagnetic radiating elements relative to another element of said first array to steer a beam of the radiation of said first array independently of the orientation of a beam of the radiation of said second array.
16. The phased array antenna as defined by claim 15 wherein said first array radiating elements have a radiation characteristic of a first frequency, and said second array radiating elements have a radiation characteristic of a second frequency.
17. The phased array antenna as defined by claim 15 wherein the radiation polarization characteristic for said first array radiating elements is polarized radiation in a first direction and the radiation polarization characteristic for said second array radiating elements is polarized radiation in a second direction.
18. The system as defined by claim 17 wherein the radiation characteristic of said first array radiating elements is at a first frequency and the radiation characteristic of said second array radiating elements is at a second frequency.
19. A phased array antenna comprising:
a first array of electromagnetic radiating elements emitting radiation having characteristics of a first frequency and a first polarization;
a second array of electromagnetic radiating elements emitting radiation having the characteristics of a second frequency in a second polarization;
means for interleaving the radiating elements of said second array of electromagnetic radiating elements among the radiating elements of said first array of electromagnetic radiating elements;
at least one of the characteristics of frequency and polarization of the radiation of said first array being different from the characteristics of frequency and polarization of the radiation of said second y means for varying the phase of radiation emitted by one element of this first array of electromagnetic radiating elements relative to another element of said first array to steer a beam of the radiation of said first array independently of the orientation of a beam of the radiation of said second array; and
at least one of said first array radiating elements having a radiating aperture having dimensions less than approximately one-third wavelength of the radiation which is characteristic for that radiating element and having a matching structure to provide a radiation characteristic for that radiating element which is approximately equivalent to the radiation characteristic for a radiating element without said matching structure and having a radiating aperture whose dimensions are approximately one-half wavelength.

Claims (19)

1. A phased array antenna including groups of electromagnetic radiating elements in which the radiating elements of one group having a radiation characteristic which is of a lower frequency and is circularly polarized are interleaved with the radiating elements of a second group having a radiation characteristic which is of a higher frequency and is circularly polarized in the opposite sense to the polarization of the radiation characteristic of the first group, at least one of said radiating elements of said first group having a radiating aperture having dimensions less than one-third wavelength of the radiation which is characteristic for that radiating element, at least one of said radiating elements of said first group having a matching structure to provide a radiation characteristic for said radiating element which is substantially equal to the radiation characteristic provided for a similar radiating element having an aperture with dimensions of one-half wavelength, the radiating elements in each of said groups being so located within the phased array antenna that the dIstance between centers of the radiating elements in any one group is substantially one-half wavelength of the radiation which is characteristic to that group.
2. The system of claim 1 in which the radiating elements in at least one of each of said groups have a cylindrical form.
3. The system of claim 1 in which a plurality of the radiating elements drawn from a plurality of said groups are coaxially mounted with respect to each other.
4. A phased array antenna in which a first group of radiating elements which form a first beam of electromagnetic radiation at a first frequency are interleaved with a second group of radiating elements which form a second beam of electromagnetic radiation at a second frequency substantially equal to one-half the first frequency, individual elements of said first group of elements being located at a plurality of the intersections of a first grid formed by three sets of parallel lines which intersect to form grid cells each of which have the form of equilateral triangles a side of which is substantially equal to a half wavelength of said first radiation, the elements of said second group of elements being located at a plurality of the intersections of a second grid formed by three sets of parallel lines which intersect to form grid cells each of which have the form of equilateral triangles, a side of a grid cell of said second grid being parallel to and having a length equal to twice the length of a side of a grid cell of said first grid, an intersection of said second grid being located at the center of a grid cell of said first grid, whereby the range of scan angles of said first beam of radiation is substantially equal to the range of scan angles of said second beam of radiation.
5. The system of claim 4 in which individual radiating elements of said groups have radiating apertures whose dimensions are substantially less than one-third wavelength of the free space radiation transmitted and received by such radiating elements, each of such radiating elements having a dielectrically loaded matching structure which provides a radiation characteristic which is substantially the same as the radiation characteristic provided by an aperture of dimensions substantially one-half wavelength of said free space radiation.
6. An antenna array comprising a plurality of groups of electromagnetic radiating elements in which the radiating elements of one group of said groups imparting a first phase characteristic to radiation transmitted from said one group are interleaved with radiating elements of a second group of said groups of radiating elements, said radiating elements of said second group imparting a second phase characteristic to radiation transmitted from said second group, said second phase characteristic being variable with respect to said first phase characteristic, said radiating elements of said one group comprising a first cylindrical dielectric member and a second dielectric member coaxial to said first member for transmitting circularly polarized radiation, at least one of said radiating elements of said one group having a radiating aperture whose dimensions are less than approximately one-third wavelength of the radiation which is characteristic for that radiating element.
7. A phased array antenna comprising: a first set of electromagnetic radiating elements arranged for forming a first beam of radiation, the elements of said first set being so located within the phased array antenna that the distance between centers of these radiating elements is approximately one-half wavelength of radiation radiated by these elements; a second set of electromagnetic radiating elements arranged for forming a second beam of radiation, the radiating elements of said second set being so located within the phased array antenna that the distance between centers of the radiating elements of said second set is approximately one-half wavelength of the radiation emitted by said elements of said second set, a radiating element of said second set oF radiating elements being interleaved among the radiating elements of said first set of radiating elements such that a radiating element of said second set of radiating elements is positioned between radiating elements of said first set of radiating elements, the radiating elements of said second set being of physically smaller size than the radiating elements of said first set to permit said interleaving of said element of said second set among said elements of said first set; and means for varying the phase independently of the frequency of radiation emitted by a radiating element of said first set of radiating elements with respect to the phase of radiation emitted by another radiating element of said first set of radiating elements to permit a variation in the orientation of said first beam of radiation relative to an orientation of said second beam of radiation.
8. A phased array antenna comprising: a first set of electromagnetic radiating elements arranged for forming a first beam of radiation; a second set of electromagnetic radiating elements arranged for forming a second beam of radiation, a radiating element of said second set of radiating elements being interleaved among the radiating elements of said first set of radiating elements such that a radiating element of said second set of radiating elements is positioned between radiating elements of said first set of radiating elements; means for varying the phase independently of the frequency of radiation emitted by a radiating element of said first set of radiating elements with respect to the phase of radiation emitted by another radiating element of said first set of radiating elements to permit a variation in the orientation of said first beam of radiation relative to an orientation of said second beam of radiation; and a plurality of the radiating elements of said first set comprising a first cylindrical dielectric member, a second dielectric member coaxial to said first dielectric member for coupling to circularly polarized radiation, and reflector means responsive to a preselected sense of circularly polarized radiation for reflecting radiant energy through said first and said second dielectric members.
9. An antenna array comprising: a plurality of groups of electromagnetic radiating elements; the elements of a first group of said plurality of groups of radiating elements being arranged for forming a first electronically steerable beam of radiation; the elements of a second group of said plurality of groups of radiating elements being arranged for forming a second electronically steerable beam of radiation, the radiating elements in said second group comprising means for making them insensitive to radiation having the frequency and the polarization of the radiation of the elements of said first group; means for positioning individual elements of said second group of radiating elements among elements of said first group of radiating elements for interleaving said second group of radiating elements with said first group of radiating elements; the distance between centers of the radiating elements in any one group of said groups of radiating elements being approximately one-half wavelength of the radiation which is characteristic to that group; means for varying the phase independently of the frequency of radiation of one of said elements of said first group of radiating elements with respect to another element of said first group of radiating elements; and means for varying the phase of radiation of one element of said second group of radiating elements with respect to another element of said second group of radiating elements independently of the phases of said first group of radiating elements for independently steering a plurality of beams of radiation relative to said antenna array.
10. An antenna array comprising: a plurality of groups of electromagnetic radiating elements; a first group of said plurality of groups of radiating elements being arraNged for forming a first electronically steerable beam of radiation; a second group of said plurality of groups of radiating elements being arranged for forming a second electronically steerable beam of radiation; means for positioning individual elements of said second group of radiating elements among elements of said first group of radiating elements for interleaving said second group of radiating elements with said first group of radiating elements; means for varying the phase independently of the frequency of radiation of one of said elements of said first group of radiating elements with respect to another element of said first group of said radiating elements; means for varying the phase of radiation of one element of said second group of radiating elements with respect to another element of said second group of radiating elements independently of the phases of said first group of radiating elements for independently steering a plurality of beams of radiation relative to said antenna array; the distance between centers of the radiating elements in any one group of said groups of radiating elements being approximately one-half wavelength of the radiation which is characteristic to that group; and the radiating elements in at least one group of said groups of electromagnetic radiating elements having radiating apertures having dimensions which are less than approximately one-third wavelength of the radiation which is characteristic for such radiating elements, and in which the dimensions of the radiating apertures of said antenna array equal approximately the dimensions of the radiating aperture formed by an antenna array of the radiating elements of at least one of the groups of said groups of electromagnetic radiating elements.
11. A phased array antenna comprising: a first array of electromagnetic radiating elements emitting radiation having characteristics of a first frequency and a first polarization; a second array of electromagnetic radiating elements emitting radiation having the characteristics of a second frequency and a second polarization; means for positioning the radiating elements of said second array of electromagnetic radiating elements within cells of a grid composed of lines interconnecting the radiating elements of said first array of electromagnetic radiating elements; at least one of the characteristics of frequency and polarization of the radiation of said first array being different from the characteristics of frequency and polarization of the radiation of said second array; the distance between centers of the radiating elements in any one array of said arrays of radiating elements being approximately one-half wavelength of the radiation which is characteristic to that array; means for varying the frequency of radiation of said first array independently of the frequency of radiation of said second array; and means for varying the phase independently of the frequency of radiation emitted by one element of said first array of electromagnetic radiating elements relative to another element of said first array to permit steering of a beam of the radiation of said first array relative to a beam of the radiation of said second array.
12. The system as defined by claim 11 including means for steering a beam of radiation formed by the radiating elements of said first array independently of a beam of radiation formed by the radiating elements of said second array.
13. The system as defined by claim 12 in which the radiating elements of said first array are spaced with reference to the radiating elements of said second array in a configuration which provides a range of scan angles of said beam of radiation formed by radiating elements of said first array which is substantially the same as the range of scan angles of the beam of radiation formed by the radiating elements of said second array.
14. The system as defined by claim 12 in which the radiating elements of said first array are spaced with reference to the radiating elements of said second array to provide a range of scan angles in the radiation pattern of the radiating elements of said first array which is substantially the same as the range of scan angles in the radiation pattern of radiating elements of said second array.
15. A phased array antenna comprising: a first array of electromagnetic radiating elements emitting radiation having characteristics of a first frequency and a first polarization; a second array of electromagnetic radiating elements emitting radiation having the characteristics of a second frequency and a second polarization, the elements of said second array comprising means for making these elements insensitive to radiation having the frequency and polarization of the radiation of elements of said first array; means for interleaving the radiating elements of said second array of electromagnetic radiating elements among the radiating elements of said first array of electromagnetic radiating elements; the distance between centers of the radiating elements in any one array of said arrays of radiating elements being approximately one-half wavelength of the radiation which is characteristic to that array; at least one of the characteristics of frequency and polarization of the radiation of said first array being different from the characteristics of frequency and polarization of the radiation of said second array; and means for varying the phase of radiation emitted by one element of said first array of electromagnetic radiating elements relative to another element of said first array to steer a beam of the radiation of said first array independently of the orientation of a beam of the radiation of said second array.
16. The phased array antenna as defined by claim 15 wherein said first array radiating elements have a radiation characteristic of a first frequency, and said second array radiating elements have a radiation characteristic of a second frequency.
17. The phased array antenna as defined by claim 15 wherein the radiation polarization characteristic for said first array radiating elements is polarized radiation in a first direction and the radiation polarization characteristic for said second array radiating elements is polarized radiation in a second direction.
18. The system as defined by claim 17 wherein the radiation characteristic of said first array radiating elements is at a first frequency and the radiation characteristic of said second array radiating elements is at a second frequency.
19. A phased array antenna comprising: a first array of electromagnetic radiating elements emitting radiation having characteristics of a first frequency and a first polarization; a second array of electromagnetic radiating elements emitting radiation having the characteristics of a second frequency in a second polarization; means for interleaving the radiating elements of said second array of electromagnetic radiating elements among the radiating elements of said first array of electromagnetic radiating elements; at least one of the characteristics of frequency and polarization of the radiation of said first array being different from the characteristics of frequency and polarization of the radiation of said second array; means for varying the phase of radiation emitted by one element of this first array of electromagnetic radiating elements relative to another element of said first array to steer a beam of the radiation of said first array independently of the orientation of a beam of the radiation of said second array; and at least one of said first array radiating elements having a radiating aperture having dimensions less than approximately one-third wavelength of the radiation which is characteristic for that radiating element and having a matching structure to provide a radiation characteristic for that radiating element which is approximately equivalent to the radiation characteristic for a radiating element without said matching structure and having a radiating aperture whose dimensions are approximately one-half wavelength.
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Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3761943A (en) * 1972-07-21 1973-09-25 Us Navy Dual-band array antenna
US3818490A (en) * 1972-08-04 1974-06-18 Westinghouse Electric Corp Dual frequency array
US4343005A (en) * 1980-12-29 1982-08-03 Ford Aerospace & Communications Corporation Microwave antenna system having enhanced band width and reduced cross-polarization
US5233356A (en) * 1986-07-29 1993-08-03 Hughes Aircraft Company Low sidelobe solid state array antenna apparatus and process for configuring an array antenna aperture
EP0618641A2 (en) * 1993-03-31 1994-10-05 Hughes Aircraft Company Ultra wideband phased array antenna
WO2000046876A1 (en) * 1999-02-05 2000-08-10 Thomson-Csf Antenna with double-band electronic scanning, with active microwave reflector
US6218988B1 (en) * 1999-03-05 2001-04-17 Nec Corporation Array antenna transmitter with a high transmission gain proportional to the number of antenna elements
US6275188B1 (en) * 2000-02-17 2001-08-14 Trw Inc. Nulling direct radiating array
FR2812457A1 (en) * 2000-07-28 2002-02-01 Thomson Csf ACTIVE BI-POLARIZATION MICROWAVE REFLECTOR, PARTICULARLY FOR AN ELECTRONICALLY BALANCED ANTENNA
WO2003028154A1 (en) 2001-09-27 2003-04-03 Raytheon Company Planar reflector
US20060214836A1 (en) * 2005-03-24 2006-09-28 Izhak Baharav System and method for pattern design in microwave programmable arrays
US20060214833A1 (en) * 2005-03-24 2006-09-28 Izhak Baharav System and method for microwave imaging using an interleaved pattern in a programmable reflector array
FR2949609A1 (en) * 2009-08-25 2011-03-04 Thales Sa Active reflectarray antenna, has radiation cells sending signal with phase shift, and piston formed by head that is positioned such that length between input of waveguide and head defines value of phase shift of sent signal
US20150207226A1 (en) * 2014-01-22 2015-07-23 Andrew Stan Podgorski Broadband Electromagnetic Radiators and Antennas
US20180113210A1 (en) * 2016-10-21 2018-04-26 Waymo Llc Mountable Radar System

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3243818A (en) * 1962-08-22 1966-03-29 Hughes Aircraft Co Dual band slot antenna having common waveguide with differing slots, each individualto its own band
US3259902A (en) * 1961-10-04 1966-07-05 Dorne And Margolin Inc Antenna with electrically variable reflector
US3267477A (en) * 1964-04-28 1966-08-16 Orville G Brickey Dual frequency microwave antenna
US3281851A (en) * 1963-05-24 1966-10-25 Hughes Aircraft Co Dual mode slot antenna
US3480958A (en) * 1965-11-29 1969-11-25 Csf Electronic scanning antenna
US3482248A (en) * 1967-07-31 1969-12-02 Us Army Multifrequency common aperture manifold antenna
US3500422A (en) * 1966-11-03 1970-03-10 Us Navy Sub-array horn assembly for phased array application
US3518689A (en) * 1967-03-06 1970-06-30 North American Rockwell Frequency-sensitive cross-scanning antenna
US3518695A (en) * 1967-09-07 1970-06-30 Collins Radio Co Antenna array multifrequency and beam steering control multiplex feed
US3553706A (en) * 1968-07-25 1971-01-05 Hazeltine Research Inc Array antennas utilizing grouped radiating elements

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3259902A (en) * 1961-10-04 1966-07-05 Dorne And Margolin Inc Antenna with electrically variable reflector
US3243818A (en) * 1962-08-22 1966-03-29 Hughes Aircraft Co Dual band slot antenna having common waveguide with differing slots, each individualto its own band
US3281851A (en) * 1963-05-24 1966-10-25 Hughes Aircraft Co Dual mode slot antenna
US3267477A (en) * 1964-04-28 1966-08-16 Orville G Brickey Dual frequency microwave antenna
US3480958A (en) * 1965-11-29 1969-11-25 Csf Electronic scanning antenna
US3500422A (en) * 1966-11-03 1970-03-10 Us Navy Sub-array horn assembly for phased array application
US3518689A (en) * 1967-03-06 1970-06-30 North American Rockwell Frequency-sensitive cross-scanning antenna
US3482248A (en) * 1967-07-31 1969-12-02 Us Army Multifrequency common aperture manifold antenna
US3518695A (en) * 1967-09-07 1970-06-30 Collins Radio Co Antenna array multifrequency and beam steering control multiplex feed
US3553706A (en) * 1968-07-25 1971-01-05 Hazeltine Research Inc Array antennas utilizing grouped radiating elements

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3761943A (en) * 1972-07-21 1973-09-25 Us Navy Dual-band array antenna
US3818490A (en) * 1972-08-04 1974-06-18 Westinghouse Electric Corp Dual frequency array
US4343005A (en) * 1980-12-29 1982-08-03 Ford Aerospace & Communications Corporation Microwave antenna system having enhanced band width and reduced cross-polarization
US5233356A (en) * 1986-07-29 1993-08-03 Hughes Aircraft Company Low sidelobe solid state array antenna apparatus and process for configuring an array antenna aperture
EP0618641A2 (en) * 1993-03-31 1994-10-05 Hughes Aircraft Company Ultra wideband phased array antenna
EP0618641A3 (en) * 1993-03-31 1995-09-20 Hughes Aircraft Co Ultra wideband phased array antenna.
US6437752B1 (en) 1999-02-05 2002-08-20 Thomson-Cfs Antenna with double-band electronic scanning, with active microwave reflector
WO2000046876A1 (en) * 1999-02-05 2000-08-10 Thomson-Csf Antenna with double-band electronic scanning, with active microwave reflector
FR2789521A1 (en) * 1999-02-05 2000-08-11 Thomson Csf TWO-BAND ELECTRONIC SCANNING ANTENNA WITH ACTIVE MICROWAVE REFLECTOR
US6218988B1 (en) * 1999-03-05 2001-04-17 Nec Corporation Array antenna transmitter with a high transmission gain proportional to the number of antenna elements
US6275188B1 (en) * 2000-02-17 2001-08-14 Trw Inc. Nulling direct radiating array
JP3490401B2 (en) 2000-02-17 2004-01-26 ティーアールダブリュー・インコーポレーテッド Nulling direct radiation array
JP2004505582A (en) * 2000-07-28 2004-02-19 タレス Dual-polarization active microwave reflector, especially for electronic scanning antennas
WO2002011238A1 (en) * 2000-07-28 2002-02-07 Thales Active dual-polarization microwave reflector, in particular for electronically scanning antenna
FR2812457A1 (en) * 2000-07-28 2002-02-01 Thomson Csf ACTIVE BI-POLARIZATION MICROWAVE REFLECTOR, PARTICULARLY FOR AN ELECTRONICALLY BALANCED ANTENNA
US6703980B2 (en) 2000-07-28 2004-03-09 Thales Active dual-polarization microwave reflector, in particular for electronically scanning antenna
WO2003028154A1 (en) 2001-09-27 2003-04-03 Raytheon Company Planar reflector
US6768468B2 (en) 2001-09-27 2004-07-27 Raytheon Company Reflecting surfaces having geometries independent of geometries of wavefronts reflected therefrom
US20060214833A1 (en) * 2005-03-24 2006-09-28 Izhak Baharav System and method for microwave imaging using an interleaved pattern in a programmable reflector array
US20060214836A1 (en) * 2005-03-24 2006-09-28 Izhak Baharav System and method for pattern design in microwave programmable arrays
US7333055B2 (en) * 2005-03-24 2008-02-19 Agilent Technologies, Inc. System and method for microwave imaging using an interleaved pattern in a programmable reflector array
DE102005062901B4 (en) * 2005-03-24 2011-12-01 Agilent Technologies, Inc. (N.D.Ges.D. Staates Delaware) System and method for microwave imaging using a nested pattern in a programmable reflector array
US8289199B2 (en) * 2005-03-24 2012-10-16 Agilent Technologies, Inc. System and method for pattern design in microwave programmable arrays
FR2949609A1 (en) * 2009-08-25 2011-03-04 Thales Sa Active reflectarray antenna, has radiation cells sending signal with phase shift, and piston formed by head that is positioned such that length between input of waveguide and head defines value of phase shift of sent signal
US20150207226A1 (en) * 2014-01-22 2015-07-23 Andrew Stan Podgorski Broadband Electromagnetic Radiators and Antennas
US20180113210A1 (en) * 2016-10-21 2018-04-26 Waymo Llc Mountable Radar System

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