US3553692A - Antenna arrays having phase and amplitude control - Google Patents

Antenna arrays having phase and amplitude control Download PDF

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Publication number
US3553692A
US3553692A US583552A US3553692DA US3553692A US 3553692 A US3553692 A US 3553692A US 583552 A US583552 A US 583552A US 3553692D A US3553692D A US 3553692DA US 3553692 A US3553692 A US 3553692A
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array
radiators
radiator
phase
waves
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Serge V Drabowitch
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Compagnie Francaise Thomson Houston SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
    • H01Q21/22—Antenna units of the array energised non-uniformly in amplitude or phase, e.g. tapered array or binomial array
    • 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
    • H01Q3/26—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 relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture

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  • This invention provides improved antenna arrays having characteristics that are matched with the geometric configuration of the electromagnetic waves that are to be radiated (i.e. transmitted from or received) by the array, for optimal performance. Such arrays have a greatly increased angular range of directivity.
  • the spacing of the individual radiators of the array, the field-strength-distribution pattern of the energy fed to or from the individual radiators, and the phase-distribution pattern of said feed energy across the array are so predetermined and correlated that the behavior of the array as a whole is made to be substantially identical with that of an imaginary, coherently radiating aperture having the same overall configuration as the array, in respect to waves of the prescribed geometric configuration.
  • antenna arrays consisting of a plurality of individual, elementary antennas or radiators spaced along a predetermined direction to provide a linear array, or along each of two coordinate directions to provide a two-dimensional or surface array.
  • Such arrays have made it possible to achieve desired directional diagrams and radiate waves having prescribed geometric configurations, for example, plane waves propagating in a prescribed direction, or spherical waves centered at a prescribed focus or source point.
  • phase shifters In arrays of this type, it is known to feed energy to and from the individual radiators by way of phase shifters, and so to adjust the phase shifters that the phase distribution of the electromagnetic energy across the array is made to be approximately the same as that of a coherent wave having a prescribed configuration.
  • the phase shifters it is obvious for example that if all the phase shifters are adjusted in like manner, then the array will radiate a plane wave propagating in a direction normal to the array. Suitable difierential adjustment of the phase shifts makes it possible to simulate in an approximate manner coherent waves having any of various prescribed geometric characteristics.
  • FIG. 1 schematically illustrates a simple linear array as used in a system according to the invention for radiating plane waves of prescribed direction over a wide scanning range;
  • FIG. 2 illustrates part of the improved array in somewhat greater detail, together with the associated fieldstrength-distribution pattern used according to the invention
  • FIG. 3 shows a preferred consruction of an array according to the invention, using paired multimode radiators
  • FIG. 4 is a curve illustrating a typical array factor
  • FIG. 5 schematically illustrates the geometry of an array according to the invention when used in association with a primary source radiating spherical waves.
  • the word radiate and its derivatives are to be construed with their broad meaning usual in antenna engineering, as applying to both the transmission and the reception of electromagnetic wave energy.
  • an elementary antenna or radiator is said to be radiating energy not only when it is operating to emit as waves propagating in space electromagnetic energy fed to it, but likewise when it is picking up or absorbing space waves and transferring the energy picked up therefrom to a receiver connected by a feeder junction to said radiator.
  • the word feed and its derivatives serves to describe the transfer of electromagnetic energy by way of a conductor or waveguide both to and from a radiator.
  • An array of the kind shown may be used to radiate waves of various geometric configurations. For example, it may be desired to cause the array to radiate plane parallel waves in a prescribed direction of space defined by a specified angle 0a with respect to the normal I-Z, all the plane waves being normal to such prescribed direction. This requirement arises, in particular, when the array is to be used as a directional transmitting and/ or receiving antenna system for transmitting radio energy e.g. in the form of radar pulses towards a target, and for receiving echo pulses from the target.
  • radio energy e.g. in the form of radar pulses towards a target, and for receiving echo pulses from the target
  • the normal way of controlling the space configuration of the waves radiated by an array is to control the phase distribution of the wave energy fed to (or from) the individual radiators of the array. If all the radiators are fed in parallel from a common signal source without any mutual phase displacement between the signals applied to the respective radiators, it is evident that the radiator array will radiate a planar wave propagating in the normal direction I-Z. If equal phase shifts are introduced between the signals applied to adjacent radiators of the array, the wave radiated from the array will still be planar, but will propagate in a direction inclined to the normal in one or the other sense, depending on the sign of the phase shift, by an angle a corresponding to the phase shift angle.
  • the distribution pattern of phase-shifts between the signals fed to (or from) the respective radiators of an array can be modified so as to cause the array to radiate spherical waves focused on a prescribed focal point or center, as disclosed in my co-pending application identified above and as later described.
  • Other geo metric configurations of radiated waves can similarly be obtained by controlling the phase-distribution patterns of energy fed to or from the array.
  • phase distribution between the radiators of the array is used to control the main directional lobe of the over-all radiation pattern of the array.
  • phase distribution for instance by the digital phaseshift-control means described in my said co-pending application
  • the angular position of the main lobe of the over-all radiation pattern can be varied, as for scanning purposes.
  • This type of scanning is sometimes termed electronic scanning in contrast to the more conventional mechanical scanning which involves mechanically displacing an antenna.
  • the width of the main lobe of each radiator again sets a definite limit to the maximum scanning angle achievable without excessively reducing the gain of the array.
  • Another defect of such conventional radiator arrays is that objectionable interaction or coupling occurs between adjacent radiators of the array, producing differential variations in the elementary radiation patterns of the radiators as the deflection angle (or scanning direction) is varied, with corresponding uncontrollable variations in antenna gain over the scanning range.
  • the present invention is based on the finding that the above and analogous deficiencies of conventional radiator arrays and electronic scanning systems using the same can be effectively eliminated if the field-distribution pattern, in respect to both amplitude and phase, of the energy fed to or from the individual radiators and the inter-radiator spacing are correlated, in accordance with certain definite teachings, with the spatial configuration of the waves that are to be radiated by the array.
  • This invention represents a development in the application of signal theory to antenna design and construction.
  • the theoretical principles of the application of signal theory to radio antennas have been published previously by me in LOnde Electrique, May 1965, page 550 et seq., in an article entitled Application de la Thorie du Signal aux Antennes.
  • the underlying idea can be summarized by saying that all statements and mathematical equations that are true for signal systems are also true for antenna systems, provided suitable changes are made in the variables involved so that, in essence, time is converted to space.
  • the field-distribution pattern of the energy fed to an antenna is regarded as an input signal fed to a signal transfer system, and the radiation pattern of the antenna is regarded as the output signal of the system.
  • the antenna itself then assumes the role of a signal-transfer system, such as a filter, having a certain well-defined transfer function, which governs the conversion of the input signal into the output signal.
  • a continuous radiating source corresponding in over-all shape with that of the array, such as a narrow slot-like radiating aperture of the length d.
  • the field distribution of such a continuous linear radiator can be shown to be representable by a complex function of the form P 1 1 (1) where A(x), the modulus of the complex function, represents the amplitude distribution of the electric field along the O-X axis, and (x) represents the phase-angle distribution of the electric field along said axis.
  • the frequency spectrum of a signal and the law of variation of said signal with time are Fourier transforms of each other, it can be shown that in analogous fashion the radiation pattern of a continuous radiator can be represented as the Fourier transform 111(1):) of the fielddistribution function F(x), where a is the angular coordinate as indicated in the drawing.
  • the Fourier transform will be identically zero for angles a outside of a certain angular interval (OL1, +a that is, the source does not radiate any field outside such interval. It will here be assumed that this condition is fulfilled.
  • the field function can be subjected to a sampling" operation, which is analogous to the sampling operation described by Shannon in respect to time-limited signals, and sometimes known as Shannons theorem (cf. Information Theory by Stanford Goldman, ch. II, Prentice-Hall Inc., New York 1955).
  • the complex field-distribution function F(x) given by Equation 1, above can be broken down into a sum of terms K F sin 0Z1) where k represents an integer, and A the wavelength to be radiated.
  • the factor 2 sin a Further, the field-strength distribution and phase distribution for the respective radiators of the array are taken in accordance with the terms of the sum 2.
  • Equation 2 can be rewritten in homogeneous form sin qrC-i-K) F (K g)
  • the overall radiation diagram of the array is substantially the same as the radiation diagram of the imaginary continuous radiation source, coextensive with the array, in respect to radiated waves having the prescribed configuration as described by the complex function If the complex distribution function represents an equiamplitude field-distribution pattern,
  • the array will then be made up of a series of equispaced radiators at the spacing 2 sin (1 each radiator having a field-distribution pattern of the where K represents the position of the radiator in the array. Furthermore, the phase displacement between the signals fed to (or from) adjacent radiators of the array is given by the expression It will be noted that the radiation diagram of each radiator is a sectoral diagram limited to the angular range (1 1)- The teachings of the invention will now be applied to two special cases.
  • the first case relates to the construction of a radiator array usable for large-angle electronic scanning.
  • the array may serve as an antenna array for transmitting planar waves in controllable directions within a prescribed scanning interval, and for receiving echo waves from the same directions.
  • phase shifters such as 19, 29, etc. may assume any suitable form. If the desired deflection angle or is constant, then fixed phase shifters, such as suitably predetermined lengths of waveguide, may be used. If on the other hand the angle a is to be adjustable, such as in the scanning application considered above, then adjustable phase shifters are used, conveniently the digitally controlled phase-shift units disclosed in my co-pending application identified above.
  • the radiators 1, 2, 3, must provide a field-strength-distribution pattern (or illumination law) at the fictive, continuous radiating aperture, represented by the line OX, which is of the form given by Equation 6 above.
  • the individual field patterns for the radiators 1, 2, 3, are obtained by assigning the consecutive integral values 0, l, 2, to the term K in that equation, viz.:
  • Radiators having the desired field-distribution characteristics as specified by the equations given above can be constructed in various ways, well understood by those skilled in the art. Thus, suitably disposed arrays of dipoles and reflectors may be used. However, in accordance with preferred embodiments of the present invention, especially in the s-h-f and the higher u-h-f frequency bands, the radiators of the array are constructed in the form of multimode horn radiators, as disclosed in my copending application.
  • FIG. 3 illustrates one such form of construction.
  • the array shown in that figure may be considered as consisting of a series of juxtaposed dual radiating sections 10, 20, 30, n0, adjacent ones of which have common feeder junctions 11, 21, 31, n1.
  • the dual sections 10 and n0 at the respective ends of the array are further connected at their outer sides with impedancematching loads provided by suitable shorted waveguides and respectively.
  • Each of the dual radiating sections, such as section 20 for instance includes a radiating aperture 12, 22, 32, 112 each bounded by two parallel separating walls such as 13 and 23 which extend generally along the axial mid-planes of the feeder junctions a predetermined distance inward from the plane of the radiating aperture, as shown.
  • each dual radiating section such as section 20 has a pair of oblique side walls extending from the sides of the feeder junctions 11, 21 and converging V-wise so as to define two symmetrical channels, such as 24 and 25, between said sidewalls and the aforementioned separating walls 13 and 23.
  • the channels 24 and 25 both terminate outwardly at the radiating aperture 22, while being separated from each other over at least part of their length by a central separating wall or septum 26.
  • each dual radiator section such as 20
  • the partial energies applied from the two feeder junctions such as 11 and 21, associated with that section combine at the radiating aperture such as 22 so as to provide thereat a resultant field which is the vector sum of the fields derived from the two associated feeder junctions.
  • each radiator section such as 20 comprising the two channels 24 and 25, outwardly bounded by the separating walls 13 and 23, is called a mode-selector or moder section of the radiator.
  • the moders can operate in either the transverse electric or the transversemagnetic modes, and in the illustrated embodiment transverse-electric operation is contemplated, with the E vector at the radiating aperture such as 22 extending perpendicular to the plane of the drawing.
  • a mode-selective radiator of the type just disclosed makes it readily possible to obtain at the radiating aperture thereof a fielddistribution pattern which closely approaches the function sin X 9 at any rate as regards the main or central lobe and the first side lobes of the distribution curve.
  • This is indicated in the upper part of FIG. 3, where the field amplitude distribution associated with each dual radiator section is represented above that section as a pair of symmetrical curves, one shown in full lines and the other dotted, which are respectively created by the energy applied to the respective feeders, such as 21 and 31, associated with the dual radiator section under consideration.
  • each elementary horn radiator therein has a field-amplitude-distribution pattern which is represented substantially as the central portion (main lobe and part of each of the first side lobes) of the curve sin X these distribution curves overlapping as shown.
  • phase shifters introducing progressive phase shifts such that the phases of the waves applied to adjacent feeder junctions differ by a desired constant angle, corresponding to the desired inclination angle for the plane wave radiated by the array, as earlier described.
  • the directional pattern of a linear array can be represented as a function of the form where A(0) represents the relative field strength of the array and is seen to be the product of two functions or factors.
  • Function B(0) characterizes any one of the elements of the array and represents the radiation diagram of such element
  • function (3(0) characterizes the geometry of the array and represents the radiation diagram of an array in which the individual radiators are disposed in the same manner as in the array under con sideration, but wherein said individual radiators are omnidirectional in character.
  • function C(fi) represents a curve of the form shown in FIG. 4 for a scanning direction axially of the array, that is, for the case where the plane waves radiated by the array have zero inclination.
  • FIG. 5 schematically illustrates the invention as applied to spherical, rather than plane, radiated waves.
  • the system shown in FIG. 5 comprises a primary radiator schematically indicated as the source S, e.g. a horn antenna, and a secondary radiating array comprising a series of radiators 1, 2, n, e.g. horn antennas, all positioned in mutually irradiating relation with the source S.
  • the secondary array shall receive the whole of the energy contained in the portion of the spherical wave limited to the angle 2on defined by the width d of the array without any loss in gain. If conversely it is assumed that energy is fed to the secondary radiators 1, 2, n of the array and is radiated therefrom towards the primary radiator S, it is desired that this radiant energy shall converge spherically at the point S as a focus so as to be absorbed wholly by the primary radiator without any loss (except for inevitable diffraction ring effect).
  • Equation 4 Since in this case also an equiamplitude field distribution is clearly involved (the field amplitude is constant throughout the spherical surface of the wave), the complex fielddistribution function can be written, from Equation 4, as:
  • the field-amplitude distribution of the energy fed to each radiator is in accordance with the function where k represents the serial number of the radiator in the array, and a has the value just specified.
  • Each of the radiators 1, 2, n of the array of FIG. 5 may be constructed as a multi-mode source, in a general manner similar to that shown in FIG. 3.
  • the radiators are fed by way of feeder junctions in which are interposed suitable phase shifters, adjusted to impart to the feed energy a phase shift of the value dictated by Equation 9.
  • the phase shift applied to the kth radiator of the array is seen from that equation to be
  • the individual radiators of the secondary array receive the spherical waves radiated by the primary source S under varying incidence angles, decreasing from the center to the periphery of the array.
  • the said condition contributes to assure optimal energy transfer to and from the array, in respect to the particular, here spherical, wave configuration considered.
  • each of the three basic teachings of the invention respectively relating to radiator spacing, field-strength-distribution pattern for each radiator, and phase-distribution pattern along the array, should be applied separately to each of two coordinate directions of the array, which directions are conveniently taken as mutually orthogonal. The construction of the two-dimensional array will then be completely determined.
  • A(K) and (K) are, respectively, an amplitude factor and a phase factor.
  • radiator No. 2 (K Z) we find that X varies linearly from a point P on one side of any radiator to a point P on the opposite side thereof, each of these points being spaced by a distance a/Z from the radiator axis 2, as specifically shown for radiator 2.
  • a system for radiating electromagnetic waves of a prescribed geometric configuration comprising:
  • radiators having radiant apertures equispaced in at least one row; and wave-feeding means connected to said radiators for imparting to each radiator a coherent radiation pattern substantially of the form A(K) exp j( where A is an amplitude factor, is a phase factor and X is a function of distance varying linearly along said row from 0 at a first point on one side of the radiator to 1r at a second point on the opposite side of that radiator, each of said points lying at a distance of substantially a/2 from the radiator axis where a: is the spacing between successive radiators, K being an integer counting the number of radiators from one end of said row, the functions A(K) and (K) being the same for all radiators.
  • Wavefeeding means includes individual phase shifters for said radiators.
  • phase shifters are set to impart to successive radiators progressively varying values of (,0 separated by substantially the same difference Agb for any two consecutive radiators.
  • phase shifters are set to impart to successive radiators different phase shifts establishing a substantially spherically curved overall pattern of radiation centered on a point remote from said row of apertures.
  • phase shifters are adjustable.
  • radiators are each divided into two sections lying on opposite sides of said axis, said wave-feeding means being co phasally connected to confronting sections of any two adjoining radiators.
  • a system for radiating electromagnetic waves of a prescribed geometric configuration comprising:
  • radiators having radiant apertures equispaced in at least one row, each of said radiators being divided into two symmetrical sections lying on opposite sides of an axis bisecting its aperture along said row;
  • wave-feeding means connected to said radiators for imparting to each radiator a coherent radiation pattern varying along said row from a peak on one side of said axis to a node on the opposite side with an amplitude and a phase respectively determined by a factor A(K) and a factor (K), said but variable phase differences between successive pairs wave-feeding means including a plurality of feeders of radiators.
  • phase US. Cl. X.R. shifters are adjustable to provide substantially identical 343786, 854

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US583552A 1965-10-15 1966-10-03 Antenna arrays having phase and amplitude control Expired - Lifetime US3553692A (en)

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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3631503A (en) * 1969-05-02 1971-12-28 Hughes Aircraft Co High-performance distributionally integrated subarray antenna
FR2317781A1 (fr) * 1975-07-10 1977-02-04 Hazeltine Corp Antenne a assemblage d'elements en phase, presentant un diagramme a coupure nette
FR2397722A1 (fr) * 1977-07-14 1979-02-09 Hazeltine Corp Antenne a reseau d'elements comportant des circuits de couplage
US4196436A (en) * 1978-11-14 1980-04-01 Ford Motor Company Differential backlobe antenna array
US4633258A (en) * 1984-06-07 1986-12-30 Spar Aerospace Limited Phase slope equalizer
US4758842A (en) * 1986-05-19 1988-07-19 Hughes Aircraft Company Horn antenna array phase matched over large bandwidths
US5327147A (en) * 1991-07-26 1994-07-05 Alcatel Espace Microwave array antenna having sources of different widths
US5565878A (en) * 1994-04-15 1996-10-15 Telefonaktiebolaget Lm Ericsson Distribution network
US6441795B1 (en) * 2000-11-29 2002-08-27 Lockheed Martin Corporation Conical horn antenna with flare break and impedance output structure
US6703980B2 (en) 2000-07-28 2004-03-09 Thales Active dual-polarization microwave reflector, in particular for electronically scanning antenna
EP2297818A1 (fr) * 2008-05-20 2011-03-23 Lockheed Martin Corporation Réseau d antennes comportant une lentille en métamatériau
US20130214736A1 (en) * 2012-02-22 2013-08-22 Electric Power Research Institute, Inc. Apparatus and method for harvesting power from an overhead transmission conductor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2470224A (en) * 2009-05-15 2010-11-17 Louis David Thomas A phase shifter for a phased array antenna

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3631503A (en) * 1969-05-02 1971-12-28 Hughes Aircraft Co High-performance distributionally integrated subarray antenna
FR2317781A1 (fr) * 1975-07-10 1977-02-04 Hazeltine Corp Antenne a assemblage d'elements en phase, presentant un diagramme a coupure nette
FR2397722A1 (fr) * 1977-07-14 1979-02-09 Hazeltine Corp Antenne a reseau d'elements comportant des circuits de couplage
US4196436A (en) * 1978-11-14 1980-04-01 Ford Motor Company Differential backlobe antenna array
US4633258A (en) * 1984-06-07 1986-12-30 Spar Aerospace Limited Phase slope equalizer
US4758842A (en) * 1986-05-19 1988-07-19 Hughes Aircraft Company Horn antenna array phase matched over large bandwidths
US5327147A (en) * 1991-07-26 1994-07-05 Alcatel Espace Microwave array antenna having sources of different widths
US5565878A (en) * 1994-04-15 1996-10-15 Telefonaktiebolaget Lm Ericsson Distribution network
US6703980B2 (en) 2000-07-28 2004-03-09 Thales Active dual-polarization microwave reflector, in particular for electronically scanning antenna
US6441795B1 (en) * 2000-11-29 2002-08-27 Lockheed Martin Corporation Conical horn antenna with flare break and impedance output structure
EP2297818A1 (fr) * 2008-05-20 2011-03-23 Lockheed Martin Corporation Réseau d antennes comportant une lentille en métamatériau
EP2297818A4 (fr) * 2008-05-20 2012-04-25 Lockheed Corp Réseau d antennes comportant une lentille en métamatériau
US8493273B2 (en) 2008-05-20 2013-07-23 Lockheed Martin Corporation Antenna array with metamaterial lens
US20130214736A1 (en) * 2012-02-22 2013-08-22 Electric Power Research Institute, Inc. Apparatus and method for harvesting power from an overhead transmission conductor
US9214827B2 (en) * 2012-02-22 2015-12-15 Electric Power Research Institute, Inc. Apparatus and method for harvesting power from an overhead transmission conductor

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SE331850B (fr) 1971-01-18
DE1541463A1 (de) 1969-07-17
DE1541463B2 (de) 1973-08-23
GB1176170A (en) 1970-01-01
FR1460075A (fr) 1966-06-17

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