US3445851A - Polarization insensitive microwave energy phase shifter - Google Patents
Polarization insensitive microwave energy phase shifter Download PDFInfo
- Publication number
- US3445851A US3445851A US579914A US3445851DA US3445851A US 3445851 A US3445851 A US 3445851A US 579914 A US579914 A US 579914A US 3445851D A US3445851D A US 3445851DA US 3445851 A US3445851 A US 3445851A
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- United States
- Prior art keywords
- energy
- phase
- waveguide
- phase shift
- polarization
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- 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
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/18—Phase-shifters
- H01P1/19—Phase-shifters using a ferromagnetic device
Definitions
- the present invention relates generally to microwave energy phase shifting devices and more specifically to a passive analog ferrite phase shifter that will simultaneously support orthogonal polarizations of the electric field vectors in a phased array antenna system.
- Planar antennas of considerable height and length utilize a large number of individual elements to provide variable electrical length to collimate and steer high power electromagnetic wave energy in a predetermined wave front.
- Ferrite phase shifters utilizing the Faraday rotation effect are commonly employed to establish the controlled phase relationship of the radiated wave front in such systems where power levels are in excess of the limits tolerable by semiconductor or mechanical variable phase shifters.
- Such devices commonly consist of a longitudinally magnetized rod of a ferromagnetic material axially positioned within a hollow conductive pipe or waveguide structure and parallel to the direction of Wave propagation.
- the electric vectors of the electromagnetic waves can be phase shifted as well as delayed in time by varying the relative strength of the applied unidirectional magnetic field.
- the microwave permeability of the ferrite material is correspondingly varied to make the device electrically longer or shorter to delay or advance the propagated waves.
- the onolinearity of ferrite materials when operated at or below ferromagnetic resonance is the parameter considered in the application of such materials in microwave devices.
- phase shifters have been coupled to individual microwave transmission elements with the beam direction determined by a central computer programmer to establish the proper phase of the wave front.
- Each antenna element is coupled by a complex corporate structure type network to a high power microwave energy source and may be referred to in the art as a transmission type phased array antenna system.
- Ser. No. 322,008, filed Nov. 5, 1963, now Pat No. 3,305,867 by Aldo R. Miccioli et a1. entitled Antenna Array System and assigned to the assignee of the present invention a new concept in phased array antennas is disclosed wherein a large array of individual antenna elements, preferably passive, is optically fed from a physically and conceptually separate radiant energy generation source.
- Each of the passive elements in the array include phase shifter means together with the radiating element to collectively define the beam steering elements.
- the high power energy generator and transmitter can be designed to provide the desired peak and average powers in the most econimocal way possible and since the energy is transmitted through free space to illuminate the phased array antenna system, thousands of transmission lines required in prior art array antennas are eliminated.
- the antenna system is correspondingly lighter by the elimination of the individaully coupled transmitters.
- the disclosed optically fed antenna array system referred to in the referenced application is also 3,445,851 Patented May 20, 1969 capable of being utilized for both transmission and reception with the duplexing accomplished in the conventional manner by a single high power antenna horn and a transducer mechanism to switch the horn to a receive mode after the transmission cycle.
- This antenna array system is commonly referred to as the reflector type and the beam steering elements provide for the traversal of the energy in two directions and hence are reentrant devices.
- Such reflector type systems commonly employ passive analog phase shifters which preferably propagate circularly polarized electromagnetic energy.
- an electrical wave is said to be circularly polarized when the field thereof can be resolved vectorially into two orthogonal components of equal amplitude apart in space and 90 apart in time. If the two vectors are not of equal amplitude or if the time difference is other than 90 the wave is considered to be elliptically polarized.
- Linearly polarized waves are those in which the time phase angle reduces to zero.
- ferrite phase shifters employed in optically fed phased array antenna systems have been polarization sensitive when the preferred circular polarized waves are utilized.
- a signal is transmitted, for example right hand circular
- the antenna element after the energy traverses the phase shifter in both directions would radiate left hand circular polarized waves.
- Such polarization sensitivity limits the utility of the system and leads to reception of undesirable target data such as rain clutter.
- right hand circular polarization is defined as an electromagnetic wave which is propagated in a manner similar to that of the right hand screw so that when traveling away from the observer its observed direction of rotation is clockwise.
- the term left hand circular polarization will be considered as being in the opposite direction of rotation or counterclockwise.
- a further object of the present invention is the provision of a one port reentrant ferrite phase shifter for reflector type optically fed phased array antenna sys tems wherein the phase shift is identical for circular, horizontal or vertical polarized waves and any combinations thereof.
- a still further object of the present invention is the operation of a ferrite phase shifter of the Faraday rotator type having inherent nonreciprocal phase-current characteristics in a reciprocal manner to shift the electrical phase of microwave energy having any orthogonal distribution of the electromagnetic field vectors.
- FIG. 1 is a diagrammatic presentation of a reflector type optically fed phased array antenna system
- FIG. 2 is a diagrammatic presentation and accompanying explanatory matter of a prior art phase shifter employed in reflector type phased array antenna systems;
- FIG. 3 is a diagrammatic illustration of the embodiment of the present invention.
- FIG. 4 is a graph illustrative of the phase-current characteristics of a ferrite phase shifter propagating two types of circular polarized energy.
- FIG. 5 is an isometric view, partly in section, of an illustrative polarization insensitive ferrite phase shifter according to the present invention.
- FIG. 1 is illustrative of a reflector type optically fed phased array antenna system in accordance with the teachings of the co-pending patent application.
- Reentrant type phase shifters 2 are incorporated in each of the antenna passive beam steering elements which collectively define the array antenna 4.
- radiating elements 6 for receiving the uncollimated energy and emitting the steered beam are provided.
- a high power electromagnetic wave generator, shown generally as transmitter 8 is disposed at a point distant from the array antenna and the energy is radiated by means of a transmitter horn 10 of any of the well known structures in the art.
- a circular polarizer 12 may be incorporated at the exit channel of the horn as well as a two mode transducer in order that the over-all system may be utilized in duplexing of transmit and receive signals as will be hereinafter evident. In such operation a suitable receiver 16 will be coupled to the same horn.
- the ferrite phase shifters 2 are initially set by adjusting the coil current of the magnetic field producing means so as to provide an effective electrical length across the surface of the array antenna with the coil current supplied by means of leads 18 from the programmer-20.
- the microwave energy from the transmitter horn 10 is radiated toward the array 4 in a divergent beam designated A in the drawing.
- Each element of the array is positioned within a circular waveguide channel and terminated at the end by short circuit means 22.
- the divergent rays emanating from the transmitter horn 10 are collimated and converted into a plane wave front of uniform phase designated by the letter B. Any desired amount of phase shift may be imposed upon the divergent beam by programming the appropriate current through the magnetic field producing means of the individual ferrite phase shifters so as to steer the beam in the desired direction.
- the beam direction is designated C and it is evident that energy originating from this direction will be received by the array antenna, phase shifted and reflected back towards the transmitter horn.
- Duplexing operation is therefore permissible through the utilization of the two-mode transducer with appropriate switching to couple the receiver apparatus 16 in the system.
- One of the advantages of the reflector type optically fed system is that since energy is passed through the ferrite phase shifters twice, the amount of phase shift realized and accompanying adjustment of the over-all electrical length is achieved utilizing approximately one-half the ferrite material required in the so-called transmission type two port systems. It may also be noted that the manner of placement of the transmitter horn is well known to those skilled in the art and may be off-set with the electrical path lengths equalized by suitable adjustment of the currents of the phase shifters within the passive antenna elements. In addition, it may be desirable to utilize the Cassegrainian type optically fed antenna horn which is also considered as well known in the art and not requiring further elaboration in this description.
- the phase shifter employs a ferrite rod 24 of a predetermined length centrally located within a circular waveguide 26 which is preferred for supporting circularly polarized waves.
- a longitudinal magnetic field is applied to the rod by means of a solenoid (not illustrated) encircling the waveguide 26 in the manner well known in the art.
- a unidirectional current and the direction of the windings of the solenoid insure that the direction of magnetization is in the appropriate direction of propagation to achieve the microwave permeability characteristics desired.
- Short circuit means 28 by any suitable conductive member at one end of the antenna element provides for the reentrant operation of the device in the array antenna system. More particularly, both rotation of the plane of polarization and the phase shift of waves transmitted through the ferrite device of the type under consideration are functions of left and right hand circularly polarized phase constants, fully described in an article by M. G. Sakiotis and H. N. Chait, entitled, Ferrites at Microwaves, Proceeding I.R.E., vol. 41, pp. 87-93, Jan. 1953.
- phase delay implies that the effective electrical length of the over-all phase shifter becomes longer due to the changes in the microwave permeability of the ferrite material.
- left hand circular polarization input results in an output which is delayed in phase for positive currents and advanced in phase for negative currents. Since different values of phase shift are obtained for the positive and negative current the illustrative phase shifter is commonly referred to as a nonreciprocal device. It may also be noted that reversing the sense of the input circular polarization between right hand and left hand has the same effect upon the phase-current characteristics as reversing the coil current.
- phase shifter is used as a passive antenna beam steering element the correct or predetermined phase shift will be provided for only one sense of circular polarization if the magnetic field is maintained at the same polarity.
- the array antenna is utilized for both transmit and receive cycles it will then be necessary to reverse the magnetic field polarities to assist in the rejection of rain clutter in target definition.
- reference is directed to the text by M. I. Skolnik, Introduction to Radar Systems, McGraw-Hill Book Company, 1962, pp. 546-551. This problem then imposes a severe limitation upon the over-all operation and required ircuitry in the design of the antenna system with accompanying increase in cost and complexity.
- a ferrite phase shifter which is inherently nonreciprocal may be operated in a reciprocal manner in an optically fed reflector type antenna array system and be polarization insensitive which results in the same value for phase shift for either right hand or left hand circular polarization.
- the over-all phase shift will be independent of the coil current direction and consequently the device will be reciprocal from the standpoint of both current polarity and polarization.
- the ferrite phase shifter of the present invention comprises a radiating element 38, a ferrite rod phase shifting section 40, and matching transformer section 42 and a short circuit 44 at the closed end of the over-all device.
- a selective reflector means 46 is disposed intermediate to the ferrite phase shifter section and the short circuited end to thereby impose a time delay on one orthogonal component of the circularly polarized wave while the remaining component is propagated in order that upon reflection by the short circuit the wave energy will have the same sense of polarization but an additional 180 phase shift as that traversing the ferrite phase shifter during the first traversal.
- the net phase shift provided by the reentrant device will be the same for either polarization of the microwave energy.
- the selective reflector means preferably comprises a polarization inverter or circular polarizer such as a onequarter wavelength plate or a gridded structure whereby selective delay in phase by 90 (a quarter-wavelength) is applied to the circularly polarized electric vectors in a direction both down and back through the antenna element to result in an over-all delay of 180.
- a polarization inverter or circular polarizer such as a onequarter wavelength plate or a gridded structure whereby selective delay in phase by 90 (a quarter-wavelength) is applied to the circularly polarized electric vectors in a direction both down and back through the antenna element to result in an over-all delay of 180.
- any anisotropic dielectric material having a dielectric constant of less than unity may be substituted for the quarter-wave plate or parallel grid structure with similar results.
- a structure comprising alternate layers of polystyrene and polyfoam is exemplary of such an anisotropic dielectric material.
- FIG. 4 the theory of the reciprocal polarization insensitive operation of my novel phase shifter incorporating a selective reflector and short circuit will be explained as presently understood.
- the coordinates of the graph are phase shift #1 along the vertical axis and current I along the horizontal axis.
- Curve 50 is a plot of phasecurrent characteristics of a right hand circularly polarized wave (RHP) and as previously noted for negative current values a phase delay is provided while for positive currents a phase advance.
- Curve 52 indicates the phase-current characteristics for left and circular polarization (LI-1P) with a phase advance for negative coil currents and a phase delay for positive currents.
- RHP right hand circularly polarized wave
- LI-1P left and circular polarization
- the passive antenna element is provided with preset magnetic bias indicated by the 1 and dotted line 54
- the reciprocal operation of the phase shifter may be described. If the incident energy polarization from the antenna horn is left hand circular, the forward traveling wave receives a phase delay & indicated by dotted line 56 during the first traversal through the ferrite phase shifter. Due to the disposition of the circular polarizer (quarter-wave plate) after the phase shifter section and before the short circuit, one orthogonal component will be unaffected while the mutually perpendicular one is speeded up.
- the reflected wave from the short circuit or what may be referred to as the backward wave upon recombining of the components becomes a mirror image of the original wave or spatially oriented 180 out of phase with respect to the input polarization. Consequently, the wave now receives a phase advance Q51 in passing through the phase shifter the second time.
- phase advance is simply negative phase delay
- the total phase shift after the reentrant path is simply a delay of or as indicated by the dotted line 58.
- the phase advance after the first traversal will be 5 and after reflection and traversal through the circular polarizer section a phase delay of 5 is provided.
- the two phase shifts again to arrive at the same net value of dr and the device is completely reciprocal in that input right hand or left hand circularly polarized waves are received and radiated with the same net phase shift.
- the receiving cycle of the operation will be polarization insensitive and the phase shifter of the invention will work equally well with linearly polarized waves as well as elliptical waves since any of these waves can be duplicated by the sum of two circular orthogonal vectors.
- phase shifter is therefore polarization insensitive and the net phase shift is independent of the coil current direction and consequently the disclosed device which is inherently a non-reciprocal structure may be operated in a reciprocal manner from the standpoint of both current polarity and polarization which is highly desirable in reflector type optically fed array antenna systems.
- FIG. 5 is illustrative of an exemplary embodiment of the invention of a reentrant type phase shifter.
- the open end is enclosed by a radiating element 60, preferably of a dielectric material with the impedance characteristics required to transform the free space input and output electromagnetic energy for propagation within the ferritephase shifter section 62.
- the ferrite element 64 in the configuration of an elongated cylindrical rod of a pre-determined length in accordance with the frequency of operation and phase shift desired is positioned within the cylindrical waveguide 66 by means of a low-loss dielectric material 68, such as for example quartz.
- a low-loss dielectric material 68 such as for example quartz.
- Other well known materials such as Teflon for supporting the ferrite ele' ment may be employed.
- the magnetic field producing means such as a solenoid 70 encirles the circular waveguide 66 and may consist of many thousand turns of a suitable conductive wire connected by means of leads 72 to an appropriate undirectional voltage source to provide the desired magnetic field bias.
- the selective reflector means 74 is disposed along the axis of the ferrite element and intermediate to this element and the short circuit 76 disposed at the closed end of the phase shifter.
- the one-quarter wavelength conductive plate 78 is disposed angularly' within the outer conductive body member 80in such a manner as to change the spatial orientation of the horizonal and vertical electric field vectors of the electromagnetic energy traversing the phase shifter in both directions by the
- the plate member 78 is oriented diametrically at an angle of 45 in the manner of the circular polarization structures employed in wave transmission devices.
- a card or vane of a dielectric material may similarly be employed in the selective reflector section.
- any anisotropic dielectric material such as alumina maybe employed in this section.
- a matching transformer 82 of a dielectric material such as quartz is provided.
- a reentrant polarization insensitive electromagnetic wave energy phase shifter comprising:
- a section of waveguide adapted to receive and propagate electromagnetic wave energy having fields polarized in a predetermined plane
- ferromagnetic means to produce a first predetermined value of electrical phase shift of energy passing through said waveguide in a forward direction
- conductive means enclosing one end of said waveguide to present a short circuit and return in a reverse direction substantially all energy incident thereon;
- said reflector means defining structure having an electrical length of one-quarter of a wavelength of said energy to yield a 180 phase difference in the orthogonal distribution of the field-s of the reverse directed wave energy whereupon a second value of phase shift is introduced upon traversal through the ferromagnetic means;
- the reflected energy having a total electrical phase shift of the difference between the first and second values and having the same sense of polarization orientation as the received energy.
- a reentrant polarization insensitive electromagnetic Wave energy phase shifter comprising:
- magnetic field producing means encircling said Waveguide adjacent to said ferrite element to provide a predetermined phase shift in the circularly polarized energy passing through said element in opposing directions;
- Waveguide being closed at one end to short circuit and reflect in a reverse direction substantially all energy incident thereon;
- a polarization inverter including a one-quarter wavelength long conductive vane member diametrically disposed within such waveguide intermediate to the closed end and said ferrite element to produce a phase difference of 180 in the orthogonal distribution of the field vectors compositely defining said reflected circularly polarized waves whereupon a second value of phase shift is introduced upon traversal through the ferrite element;
- the reflected output energy having a net electrical phase shift equal to the difference between the first and second values and having the same sense of polarization of the input circularly polarized wave energy.
- a reentrant polarization insensitive electromagnetic wave energy phase shifter according to claim 2 wherein said polarization inverter comprises a body of an anisotropic dielectric material one-quarter of a Wavelength of said energy in length.
- a device for providing a variable electrical phase shift of electrimagnetic wave energy comprising:
- waveguide means for receiving and launching at one end said wave energy
- a ferrite element disposed along the longitudinal axis of said waveguide
- magnetic field producing means including an electric field coil concentrically wound around said waveguide in the region'of said ferrite element and a source of unidirectional current connected thereto to thereby alter the energy permeability of the ferrite element;
- short circuiting means disposed at the opposing end of said waveguide to reflect substantially all energy incident thereon;
- a fixed circular polarizing structure disposed intermediate to said short circuiting means and said ferrite element to introduce a phase difference in the orthogonal distribution of the electric field vectors of said energy between the point of exit after the first traversal through said ferrite element and the point of entry after deflection to traverse the ferrite element in the reverse direction.
- a device according to claim 4 wherein said circular polarizing structure comprises a diametrically disposed vane member one-quarter of a wavelength of said energy in length.
- a device according to claim 4 wherein said circular polarizing structure comprises an anisotropic dielectric material of predetermined length.
- means for collimating and directing said transmitted energy in a desired direction including an array of reentrant variable electrical elements
- each of said elements comprising a section of waveguide
- a radiating element enclosing one end of said waveguide to receive and launch said energy; ferromagnetic means to produce a predetermined electrical phase shift in energy traversing said waveguide in opposing directions, the value of phase shift being different for each direction to yield a net phase shift represented by the difference in said values;
- waveguide shorting means enclosing the opposing end of said waveguide to reverse the direction of travel of said energy through said element
- selective reflector means disposed between said shorting and ferromagnetic means to introduce a 180 phase differential in one orthogonal electric vector of said energy relative to the allied mutually perpendicular vector and thereby invert the orientation of said vectors of said energy traversing the space defined between said shorting means and the adjacent end of said ferromagnetic means.
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Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US57991466A | 1966-09-16 | 1966-09-16 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3445851A true US3445851A (en) | 1969-05-20 |
Family
ID=24318863
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US579914A Expired - Lifetime US3445851A (en) | 1966-09-16 | 1966-09-16 | Polarization insensitive microwave energy phase shifter |
Country Status (7)
Country | Link |
---|---|
US (1) | US3445851A (de) |
BE (1) | BE703455A (de) |
CH (1) | CH474870A (de) |
DE (1) | DE1591415B2 (de) |
GB (1) | GB1170370A (de) |
NL (2) | NL6712419A (de) |
SE (1) | SE326740B (de) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3534374A (en) * | 1967-12-11 | 1970-10-13 | Sylvania Electric Prod | High efficiency scanning millimeter wavelength antenna |
US3569974A (en) * | 1967-12-26 | 1971-03-09 | Raytheon Co | Dual polarization microwave energy phase shifter for phased array antenna systems |
US4576441A (en) * | 1984-03-02 | 1986-03-18 | United Technologies Corporation | Variable fresnel lens device |
US4636799A (en) * | 1985-05-03 | 1987-01-13 | United Technologies Corporation | Poled domain beam scanner |
US4639093A (en) * | 1984-03-02 | 1987-01-27 | United Technologies Corporation | Switchable bandwidth filter |
US4706094A (en) * | 1985-05-03 | 1987-11-10 | United Technologies Corporation | Electro-optic beam scanner |
US4822149A (en) * | 1984-03-02 | 1989-04-18 | United Technologies Corporation | Prismatic ferroelectric beam steerer |
US5260713A (en) * | 1988-11-14 | 1993-11-09 | Motson & Company Limited | Microwave signal receiving apparatus |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2760166A (en) * | 1951-12-27 | 1956-08-21 | Bell Telephone Labor Inc | Directional phase shifter |
US3166724A (en) * | 1961-11-24 | 1965-01-19 | Philip J Allen | Electrical frequency shifter utilizing faraday phase shifter and dual mode coupler with rotatable reflection dipole |
-
0
- NL NL135272D patent/NL135272C/xx active
-
1966
- 1966-09-16 US US579914A patent/US3445851A/en not_active Expired - Lifetime
-
1967
- 1967-09-04 GB GB40398/67A patent/GB1170370A/en not_active Expired
- 1967-09-04 BE BE703455D patent/BE703455A/xx not_active IP Right Cessation
- 1967-09-07 CH CH1253567A patent/CH474870A/de not_active IP Right Cessation
- 1967-09-08 DE DE19671591415 patent/DE1591415B2/de active Pending
- 1967-09-11 NL NL6712419A patent/NL6712419A/xx unknown
- 1967-09-15 SE SE12736/67A patent/SE326740B/xx unknown
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2760166A (en) * | 1951-12-27 | 1956-08-21 | Bell Telephone Labor Inc | Directional phase shifter |
US3166724A (en) * | 1961-11-24 | 1965-01-19 | Philip J Allen | Electrical frequency shifter utilizing faraday phase shifter and dual mode coupler with rotatable reflection dipole |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3534374A (en) * | 1967-12-11 | 1970-10-13 | Sylvania Electric Prod | High efficiency scanning millimeter wavelength antenna |
US3569974A (en) * | 1967-12-26 | 1971-03-09 | Raytheon Co | Dual polarization microwave energy phase shifter for phased array antenna systems |
US4576441A (en) * | 1984-03-02 | 1986-03-18 | United Technologies Corporation | Variable fresnel lens device |
US4639093A (en) * | 1984-03-02 | 1987-01-27 | United Technologies Corporation | Switchable bandwidth filter |
US4822149A (en) * | 1984-03-02 | 1989-04-18 | United Technologies Corporation | Prismatic ferroelectric beam steerer |
US4636799A (en) * | 1985-05-03 | 1987-01-13 | United Technologies Corporation | Poled domain beam scanner |
US4706094A (en) * | 1985-05-03 | 1987-11-10 | United Technologies Corporation | Electro-optic beam scanner |
US5260713A (en) * | 1988-11-14 | 1993-11-09 | Motson & Company Limited | Microwave signal receiving apparatus |
Also Published As
Publication number | Publication date |
---|---|
DE1591415B2 (de) | 1971-12-09 |
GB1170370A (en) | 1969-11-12 |
SE326740B (de) | 1970-08-03 |
CH474870A (de) | 1969-06-30 |
BE703455A (de) | 1968-02-01 |
NL135272C (de) | |
NL6712419A (de) | 1968-03-18 |
DE1591415A1 (de) | 1971-12-09 |
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