POLARIZATION INSENSITIVE TRANSMISSION PHASE SHIFTER
United States Patent 3845421
The apparatus of the present invention constitutes a four part polarization insensitive transmission type phase shifter which utilizes a single phase shifter to provide the same amount of phase shift to two independent signals. In operation one signal progresses and passes through the phase shift section in one direction, while the remaining signal progresses through the same phase shift section in the opposite direction. Since these two signals travel through the phase shifter in the opposite sense, reasonably good isolation between these two signals is achieved.
US Patent References:
NONRECIPROCAL FERRITE PHASE-SHIFTER FOR SIMULTANEOUSLY PHASE SHIFTING TE01 AND TE10 MODES IN OPPOSITE DIRECTIONS
Hai et al. - July 1970 - 3519956
PHASE-SHIFTING MEANS
Hord et al. - December 1971 - 3626335
NONRECIPROCAL FERRITE PHASE-SHIFTER FOR SIMULTANEOUSLY PHASE SHIFTING TE01 AND TE10 MODES IN OPPOSITE DIRECTIONS
Hai et al. - July 1970 - 3519956
PHASE-SHIFTING MEANS
Hord et al. - December 1971 - 3626335
Inventors:
Charlton, Donald A. (Huntington Beach, CA)
Chen, Chao C. (Cerritos, CA)
Chen, Chao C. (Cerritos, CA)
Application Number:
05/430340
Publication Date:
10/29/1974
Filing Date:
01/02/1974
View Patent Images:
Export Citation:
Assignee:
Hughes Aircraft Company (Culver City, CA)
Primary Class:
Other Classes:
333/21A, 333/1.100
International Classes:
H01P1/161; H01P1/18; H01P1/16; H03H7/20; H01P1/16
Field of Search:
333/1.1,6-11,21A,21R,31R,31A,98R,24.1,24.3,1
Primary Examiner:
Lawrence, James W.
Assistant Examiner:
Nussbaum, Marvin
Attorney, Agent or Firm:
Himes Jr., Macallister R. H. W. H.
Claims:
1. A polarization insensitive phase shifter comprising:
2. The polarization insensitive phase shifter as defined in claim 1 wherein said means coupled from said second termination of said first transducer and from said third termination of said second transudcer to said first termination of said phase shifter and said means coupled from said third termination of said first transducer and from said second termination of said second transducer to said second termination of said phase shifter
3. The polarization insensitive phase shifter as defined in claim 1 wherein said means coupled from said second termination of said first transducer and from said third termination of said second transducer to said first termination of said phase shifter and said means coupled from said third termination of said first transducer and from said second termination of said second transducer to said second termination of said phase shifter constitute third and fourth transducers, respectively, disposed at opposite extremities of said phase shifter and first and second reciprocal polarizers disposed intermediate said phase shifter and said third and
4. The polarization insensitive phase shifter as defined in claim 3 wherein said phase shifter includes means for propagating electromagnetic waves through a ferrite medium between the first and second terminals thereof, means for generating a magnetic field having flux lines parallel to the overall direction of propagation between said first and second terminals of said phase shifter, and means for reversing the polarity of said magnetic field thereby to control the direction of operation of said
5. The polarization insensitive phase shifter as defined in claim 1 wherein said first component is horizontally polarized and said second component
6. A polarization insensitive phase shifter adapted to introduce a phase delay from an input termination to an output termination, said phase shifter comprising:
7. The polarization insensitive phase shifter as defined in claim 6 wherein said bilateral phase shifting device having first and second terminations at opposite extremities thereof includes a longitudinal waveguide section capable of propagating both horizontally and vertically polarized electromagnetic waves, a ferrite material disposed along a predetermined length inside said longitudinal waveguide section, means for generating a magnetic field of predetermined intensity in a selected direction through said ferrite material parallel to the longitudinal axis of said waveguide section, and means disposed at opposite extremities of said longitudinal waveguide section for bidirectionally converting said horizontally and
8. The polarization insensitive phase shifter as defined in claim 7 wherein said means for bidirectionally converting said horizontally and vertically polarized components into circularly polarized waves constitute reciprocal
9. A polarization insensitive phase shifter comprising:
10. The polarization insensitive phase shifter as defined in claim 9 wherein the direction of operation of said first and second circulators are simultaneously reversible thereby to control the direction of operation of said polarization insensitive phase shifter.
2. The polarization insensitive phase shifter as defined in claim 1 wherein said means coupled from said second termination of said first transducer and from said third termination of said second transudcer to said first termination of said phase shifter and said means coupled from said third termination of said first transducer and from said second termination of said second transducer to said second termination of said phase shifter
3. The polarization insensitive phase shifter as defined in claim 1 wherein said means coupled from said second termination of said first transducer and from said third termination of said second transducer to said first termination of said phase shifter and said means coupled from said third termination of said first transducer and from said second termination of said second transducer to said second termination of said phase shifter constitute third and fourth transducers, respectively, disposed at opposite extremities of said phase shifter and first and second reciprocal polarizers disposed intermediate said phase shifter and said third and
4. The polarization insensitive phase shifter as defined in claim 3 wherein said phase shifter includes means for propagating electromagnetic waves through a ferrite medium between the first and second terminals thereof, means for generating a magnetic field having flux lines parallel to the overall direction of propagation between said first and second terminals of said phase shifter, and means for reversing the polarity of said magnetic field thereby to control the direction of operation of said
5. The polarization insensitive phase shifter as defined in claim 1 wherein said first component is horizontally polarized and said second component
6. A polarization insensitive phase shifter adapted to introduce a phase delay from an input termination to an output termination, said phase shifter comprising:
7. The polarization insensitive phase shifter as defined in claim 6 wherein said bilateral phase shifting device having first and second terminations at opposite extremities thereof includes a longitudinal waveguide section capable of propagating both horizontally and vertically polarized electromagnetic waves, a ferrite material disposed along a predetermined length inside said longitudinal waveguide section, means for generating a magnetic field of predetermined intensity in a selected direction through said ferrite material parallel to the longitudinal axis of said waveguide section, and means disposed at opposite extremities of said longitudinal waveguide section for bidirectionally converting said horizontally and
8. The polarization insensitive phase shifter as defined in claim 7 wherein said means for bidirectionally converting said horizontally and vertically polarized components into circularly polarized waves constitute reciprocal
9. A polarization insensitive phase shifter comprising:
10. The polarization insensitive phase shifter as defined in claim 9 wherein the direction of operation of said first and second circulators are simultaneously reversible thereby to control the direction of operation of said polarization insensitive phase shifter.
Description:
BACKGROUND OF THE INVENTION
Dual polarization capability of phase shifters is generally desirable in phased arrays so that the resulting antenna system can receive waves that are polarized. Phased arrays of this type may require as many as 10,000 or more phase shifters. Since the distance between elements of the array is determined by basic design considerations, the space that can be allocated to each phase shifter is fixed. In a conventional phased array, dual polarization capability is accomplished by using two separate sets of phase shifters, one set for each polarization. Such a phase shifter is described in U.S. Pat. No. 3,626,335 entitled "Phase Shifting Means." Thus, in addition to volume restrictions, an additional phase shifter is required together with the requisite dual mode transducers for each element of the array.
SUMMARY OF THE INVENTION
In accordance with the present invention, two orthogonal mode input-output transducers are incorporated with a conventional phase shifter which may be, for example, either the diode or the ferrite type. The transducers which are implemented at both ends of the phase shifter body are so designed that they provide a forward wave for one polarization through the variable phase shift section and a backward wave propagating in the reverse direction for the remaining orthogonally polarized wave. The forward and backward waves are arranged to obtain the same amount of phase shift when they pass through the phase shift section simultaneously in opposite directions. Isolation between the forward and backward waves depends on the impedance match condition of the input-output transducers.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a three-dimensional view of the polarization insensitive transmission phase shifter of the present invention;
FIGS. 2 and 3 show cross-sections 2--2 and 3--3 respectively;
FIGS. 4, 5 and 6 describe the transmit and receive polarization; and
FIG. 7 illustrates a dual polarization, non-reciprocal diode phase shifter.
DESCRIPTION
Referring now to FIG. 1 of the drawings, the polarization insensitive transmission phase shifter of the present invention includes loop-type input and output transducers 10,12, respectively, which are adapted to receive and transmit both vertically and horizontally polarized electromagnetic waves. In addition to the input and output transducers 10,12 the phase shifter of the present invention includes a waveguide section 13 which may be of square or circular cross-section capable of propagating both horizontally and vertically polarized electromagnetic waves. Waveguide section 13 has loop-type orthogonal transducers 14,15 at each extremity and a non-reciprocal ferrite phase shifter 16 in the center portion thereof separated from transducers 14,15 by reciprocal polarizers 17,18.
Input transducer 10 includes a vertical loop 20, as shown in the drawing, which connects through the center conductor of a coaxial transmission line 21 to a vertical loop 22 within transducer 14. In a similar manner, a vertical loop within transducer 12 connects through a coaxial line 23 to a vertical loop within the transducer 15. Further, input transducer 10 includes a horizontal loop 24, as shown in the drawing, which connects via the center conductor of a coaxial line 27 to a horizontal loop within transducer 12.
As mentioned above reciprocal polarizers 17,18 are disposed intermediate the non-reciprocal ferrite phase shift section 16 and transducers 14,15 respectively. Reciprocal polarizers 17,18 include dielectric slabs 29,30 respectively, which are disposed diagonally across the waveguide section 13 in opposite directions. In particular, FIG. 2 illustrates cross-section 2--2 of reciprocal polarizer 17 wherein dielectric slab 29 extends from the upper left corner to the lower right corner of a square waveguide section 13, as viewed in the drawing. FIG. 3, on the other hand, illustrates cross-section 3--3 of reciprocal polarizer 18 wherein dielectric slab 30 extends from the lower left corner to the upper right corner of the square waveguide section 13, as viewed in the drawing. The length of the dielectric slabs 29,30 along the waveguide should be such as to introduce a one-quarter wavelength difference in the orthogonal modes propagated therethrough.
Referring again to FIG. 1, the ferrite phase shift section 16 includes a ferrite core 32 disposed longitudinally along the center portion of waveguide Section 13. Adjacent to the outside of each sidewall of waveguide section 13 there is disposed a longitudinal electromagnetic yoke 34 which extends past the ferrite core 32 so as to produce a longitudinal controllable magnetic field therethrough. Drive wheels 35,36 encircle the waveguide section 13 for a sufficient distance to produce a longitudinal magnetic field through ferrite core 32 which returns through yokes 34. Drive wires 35,36 are momentarily connected through a reversing switch 37 across a rheostat 38 serially connected with a battery 39 whereby the ferrite core 32 remains magnetized at a constant value until drive wires 35,36 are again energized through reversing switch 37 thereby enabling a reversible, variable magnetic field to be established through the ferrite core 32 to provide the same phase shift for both emitted and incident waves as will be hereinafter explained.
In describing the operation of the polarization insensitive phase shifter of the present invention, reference is made to FIG. 4 of the drawings which shows a schematic diagram of the device of FIG. 1 wherein a magnetic field is generated from left to right through the ferrite phase shift section 16, as shown in the drawing. During transmission, incident electromagnetic waves are applied to transducer 10 which applies a vertical component 40, FIG. 5, to transducer 14 and a horizontal component 41 to transducer 15. The vertical component 40 traverses dielectric slab 29 disposed at an angle of 315° relative thereto. Vertical component 40, in turn, resolves into two equal components, one parallel to the dielectric slab 29 and the other perpendicular thereto. The length of the slab 29 is selected to delay the parallel component by 90° relative to the vertical component thereby converting component 40 into counterclockwise circularly polarized wave 42. Upon progressing through the phase shift section 16 through which a magnetic field, M from left to right as viewed in the drawing, is generated, the counterclockwise wave 42 undergoes a phase shift + φ which phase shift is retained after progressing through reciprocal polarizer 18. The reciprocal polarizer 18 delays the "undelayed" component of wave 40 by 90°, thus converting the circularly polarized wave 43 which has now undergone a phase delay of + φ back into a vertically polarized component 43. This delayed vertical component 43 is thus energized as a vertical component in transducer 12.
The horizontal component 41 propagates a distance l along coax 25 prior to being launched in transducer 15 as a horizontally polarized wave. Upon traversing the dielectric slab 30 the component normal thereto increases in phase by 90° relative to the phase of the component parallel to dielectric slab 30 thereby converting component 41 into a clockwise circularly polarized wave 44, as viewed from right to left in the drawing. Upon propagating through the phase shift section 16, circularly polarized wave 44 encounters the same magnetic field as did the wave 42, the only difference being that the waves 42,44 propagate in opposite directions, thereby minimizing any interaction therebetween. The direction of the circular polarization of the waves 42,44 relative to the direction of the magnetic field, M, are the same, i.e., the "screw sense" of the waves 42,44 are the same, so that both waves 42,44 undergo the same phase change, + φ in traversing phase shift section 16. Subsequently, the dielectric slab 29 delays the component normal to dielectric slab 30 of circularly polarized wave 44 thereby converting it back to a delayed horizontally polarized wave 45. Wave 45 propagates an additional distance l through coaxial line 27 whereby a wave 46 having a delay of 2l+φ 1 is applied to the horizontal input loop of transducer 12. Additional line can be inserted in the path of the vertical component 43 exterior to the phase shifter of the present invention to compensate for the additional distance traveled by the horizontal component 46, if this factor is critical.
To convert the operation of the phase shifter device of the present invention to receive, the direction of the magnetic field M, through phase shift section 16 is reversed by changing the position of reversing switch 37 so as to retain the same "screw sense" with the circularly polarized waves. Electromagnetic energy incident on transducer 12 includes a vertical component 50 and horizontal component 51, FIG. 6. As before, the components are separated with the vertical component 50 launched along waveguide section 13 from right to left, as viewed in the drawing, by means of transducer 15 and with the horizontal component 51 launched along waveguide section 13 from left to right, as viewed in the drawing, by means of transducer 14. Upon progressing through polarizer 18, vertical component 50 resolves into a component parallel to dielectric slab 30 and a component normal thereto. Since the wave normal to dielectric slab 30 traverses it first, the vertical component 50 is converted to a counterclockwise circularly polarized wave 52, as viewed from right to left in the drawing. With the magnetic field, M, reversed the screw sense is the same as for wave 42, FIG. 5, whereby the wave 52 appears as wave 53 at the output of phase shifter 16 delayed by the same phase shift φ 1 . Wave 53 is converted back to a vertical component 54 by reciprocal polarizer 17.
Similarly, horizontal component 51 propagates through coaxial line 27 to transducer 14 which launched as a horizontally polarized wave through polarizer 17 which converts it into clockwise circularly polarized wave 55. Since the direction of the magnetic field, M, has been reversed the "screw sense" remains the same whereby the wave 55 undergoes the same phase shift φ 1 in progressing through phase shifter 16 and appears at the output thereof as wave 56. Wave 56 is converted to horizontally polarized wave 57 by reciprocal polarizer 18. Wave 57 must propagate through coaxial line 25 to transducer 10 whence it is emitted as wave 58 with a total phase delay 0f 2l+φ 1 . The same compensation in the feed network used on transmit provides compensation for the 2l delay difference for the horizontal component 58 of an incident wave.
Referring to FIG. 7, there is shown a polarization insensitive phase shifter in accordance with the invention employing switchable circulators 60,61 in lieu of transducers 14,15 and reciprocal polarizers 17,18 thereby enabling a conventional variable phase shifter 62 to be employed therebetween. As before, transducers 64,65 are employed to provide input-output connections to the device. Circulators 60,61 are defined as having three ports designated A, B and C. In one state, an input to port A is emitted from port B, an input to port B is emitted from port C and an input to port C is emitted from port A. In an opposite states an input to port A is emitted from port C, an input to port C is emitted from port B and an input to port B is emitted from port A. Referring to FIG. 7, port B of circulators 60,61 are connected to opposite extremities of variable phase shifter 62. Transducer 64 resolves input energy into first and second orthogonal components available at terminals 67,68, respectively, which are connected, respectively, to port A of switchable circulators 60,61. Transducer 65 is adapted to combine the first and second orthogonal components applied at terminals 69,70, respectively, which are connected to port C of switchable circulators 61,60 respectively. Means for switching the circulators 60,61 is not shown.
In the operation of the device of FIG. 7 to transmit from left to right, as viewed in the drawing, the circulators 60,61 are switched to operate in a counterclockwise direction as indicated by the arrows. Thus, first and second orthogonal components from transducer 64 are applied to port A of switchable circulators 60,61, respectively, and emanate from port B thereof and propagate in opposite directions through variable phase shifter 62 whereby each wave is delayed by φ 1 . The energy delayed by φ 1 is applied to port B of the opposite circulator 60 or 61 from whence it is emitted from port C thereof and applied to terminals 69,70 of transducer 65. Transducer 65 combines the delayed orthogonal component whence the input wave delayed in phase by φ 1 is emitted from the output thereof. To reverse the direction of operation from right to left, as viewed in the drawing, the switchable circulators 60,61 are both switched to effect a flow of energy in the clockwise direction. Operation is the same as before.
Dual polarization capability of phase shifters is generally desirable in phased arrays so that the resulting antenna system can receive waves that are polarized. Phased arrays of this type may require as many as 10,000 or more phase shifters. Since the distance between elements of the array is determined by basic design considerations, the space that can be allocated to each phase shifter is fixed. In a conventional phased array, dual polarization capability is accomplished by using two separate sets of phase shifters, one set for each polarization. Such a phase shifter is described in U.S. Pat. No. 3,626,335 entitled "Phase Shifting Means." Thus, in addition to volume restrictions, an additional phase shifter is required together with the requisite dual mode transducers for each element of the array.
SUMMARY OF THE INVENTION
In accordance with the present invention, two orthogonal mode input-output transducers are incorporated with a conventional phase shifter which may be, for example, either the diode or the ferrite type. The transducers which are implemented at both ends of the phase shifter body are so designed that they provide a forward wave for one polarization through the variable phase shift section and a backward wave propagating in the reverse direction for the remaining orthogonally polarized wave. The forward and backward waves are arranged to obtain the same amount of phase shift when they pass through the phase shift section simultaneously in opposite directions. Isolation between the forward and backward waves depends on the impedance match condition of the input-output transducers.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a three-dimensional view of the polarization insensitive transmission phase shifter of the present invention;
FIGS. 2 and 3 show cross-sections 2--2 and 3--3 respectively;
FIGS. 4, 5 and 6 describe the transmit and receive polarization; and
FIG. 7 illustrates a dual polarization, non-reciprocal diode phase shifter.
DESCRIPTION
Referring now to FIG. 1 of the drawings, the polarization insensitive transmission phase shifter of the present invention includes loop-type input and output transducers 10,12, respectively, which are adapted to receive and transmit both vertically and horizontally polarized electromagnetic waves. In addition to the input and output transducers 10,12 the phase shifter of the present invention includes a waveguide section 13 which may be of square or circular cross-section capable of propagating both horizontally and vertically polarized electromagnetic waves. Waveguide section 13 has loop-type orthogonal transducers 14,15 at each extremity and a non-reciprocal ferrite phase shifter 16 in the center portion thereof separated from transducers 14,15 by reciprocal polarizers 17,18.
Input transducer 10 includes a vertical loop 20, as shown in the drawing, which connects through the center conductor of a coaxial transmission line 21 to a vertical loop 22 within transducer 14. In a similar manner, a vertical loop within transducer 12 connects through a coaxial line 23 to a vertical loop within the transducer 15. Further, input transducer 10 includes a horizontal loop 24, as shown in the drawing, which connects via the center conductor of a coaxial line 27 to a horizontal loop within transducer 12.
As mentioned above reciprocal polarizers 17,18 are disposed intermediate the non-reciprocal ferrite phase shift section 16 and transducers 14,15 respectively. Reciprocal polarizers 17,18 include dielectric slabs 29,30 respectively, which are disposed diagonally across the waveguide section 13 in opposite directions. In particular, FIG. 2 illustrates cross-section 2--2 of reciprocal polarizer 17 wherein dielectric slab 29 extends from the upper left corner to the lower right corner of a square waveguide section 13, as viewed in the drawing. FIG. 3, on the other hand, illustrates cross-section 3--3 of reciprocal polarizer 18 wherein dielectric slab 30 extends from the lower left corner to the upper right corner of the square waveguide section 13, as viewed in the drawing. The length of the dielectric slabs 29,30 along the waveguide should be such as to introduce a one-quarter wavelength difference in the orthogonal modes propagated therethrough.
Referring again to FIG. 1, the ferrite phase shift section 16 includes a ferrite core 32 disposed longitudinally along the center portion of waveguide Section 13. Adjacent to the outside of each sidewall of waveguide section 13 there is disposed a longitudinal electromagnetic yoke 34 which extends past the ferrite core 32 so as to produce a longitudinal controllable magnetic field therethrough. Drive wheels 35,36 encircle the waveguide section 13 for a sufficient distance to produce a longitudinal magnetic field through ferrite core 32 which returns through yokes 34. Drive wires 35,36 are momentarily connected through a reversing switch 37 across a rheostat 38 serially connected with a battery 39 whereby the ferrite core 32 remains magnetized at a constant value until drive wires 35,36 are again energized through reversing switch 37 thereby enabling a reversible, variable magnetic field to be established through the ferrite core 32 to provide the same phase shift for both emitted and incident waves as will be hereinafter explained.
In describing the operation of the polarization insensitive phase shifter of the present invention, reference is made to FIG. 4 of the drawings which shows a schematic diagram of the device of FIG. 1 wherein a magnetic field is generated from left to right through the ferrite phase shift section 16, as shown in the drawing. During transmission, incident electromagnetic waves are applied to transducer 10 which applies a vertical component 40, FIG. 5, to transducer 14 and a horizontal component 41 to transducer 15. The vertical component 40 traverses dielectric slab 29 disposed at an angle of 315° relative thereto. Vertical component 40, in turn, resolves into two equal components, one parallel to the dielectric slab 29 and the other perpendicular thereto. The length of the slab 29 is selected to delay the parallel component by 90° relative to the vertical component thereby converting component 40 into counterclockwise circularly polarized wave 42. Upon progressing through the phase shift section 16 through which a magnetic field, M from left to right as viewed in the drawing, is generated, the counterclockwise wave 42 undergoes a phase shift + φ which phase shift is retained after progressing through reciprocal polarizer 18. The reciprocal polarizer 18 delays the "undelayed" component of wave 40 by 90°, thus converting the circularly polarized wave 43 which has now undergone a phase delay of + φ back into a vertically polarized component 43. This delayed vertical component 43 is thus energized as a vertical component in transducer 12.
The horizontal component 41 propagates a distance l along coax 25 prior to being launched in transducer 15 as a horizontally polarized wave. Upon traversing the dielectric slab 30 the component normal thereto increases in phase by 90° relative to the phase of the component parallel to dielectric slab 30 thereby converting component 41 into a clockwise circularly polarized wave 44, as viewed from right to left in the drawing. Upon propagating through the phase shift section 16, circularly polarized wave 44 encounters the same magnetic field as did the wave 42, the only difference being that the waves 42,44 propagate in opposite directions, thereby minimizing any interaction therebetween. The direction of the circular polarization of the waves 42,44 relative to the direction of the magnetic field, M, are the same, i.e., the "screw sense" of the waves 42,44 are the same, so that both waves 42,44 undergo the same phase change, + φ in traversing phase shift section 16. Subsequently, the dielectric slab 29 delays the component normal to dielectric slab 30 of circularly polarized wave 44 thereby converting it back to a delayed horizontally polarized wave 45. Wave 45 propagates an additional distance l through coaxial line 27 whereby a wave 46 having a delay of 2l+φ 1 is applied to the horizontal input loop of transducer 12. Additional line can be inserted in the path of the vertical component 43 exterior to the phase shifter of the present invention to compensate for the additional distance traveled by the horizontal component 46, if this factor is critical.
To convert the operation of the phase shifter device of the present invention to receive, the direction of the magnetic field M, through phase shift section 16 is reversed by changing the position of reversing switch 37 so as to retain the same "screw sense" with the circularly polarized waves. Electromagnetic energy incident on transducer 12 includes a vertical component 50 and horizontal component 51, FIG. 6. As before, the components are separated with the vertical component 50 launched along waveguide section 13 from right to left, as viewed in the drawing, by means of transducer 15 and with the horizontal component 51 launched along waveguide section 13 from left to right, as viewed in the drawing, by means of transducer 14. Upon progressing through polarizer 18, vertical component 50 resolves into a component parallel to dielectric slab 30 and a component normal thereto. Since the wave normal to dielectric slab 30 traverses it first, the vertical component 50 is converted to a counterclockwise circularly polarized wave 52, as viewed from right to left in the drawing. With the magnetic field, M, reversed the screw sense is the same as for wave 42, FIG. 5, whereby the wave 52 appears as wave 53 at the output of phase shifter 16 delayed by the same phase shift φ 1 . Wave 53 is converted back to a vertical component 54 by reciprocal polarizer 17.
Similarly, horizontal component 51 propagates through coaxial line 27 to transducer 14 which launched as a horizontally polarized wave through polarizer 17 which converts it into clockwise circularly polarized wave 55. Since the direction of the magnetic field, M, has been reversed the "screw sense" remains the same whereby the wave 55 undergoes the same phase shift φ 1 in progressing through phase shifter 16 and appears at the output thereof as wave 56. Wave 56 is converted to horizontally polarized wave 57 by reciprocal polarizer 18. Wave 57 must propagate through coaxial line 25 to transducer 10 whence it is emitted as wave 58 with a total phase delay 0f 2l+φ 1 . The same compensation in the feed network used on transmit provides compensation for the 2l delay difference for the horizontal component 58 of an incident wave.
Referring to FIG. 7, there is shown a polarization insensitive phase shifter in accordance with the invention employing switchable circulators 60,61 in lieu of transducers 14,15 and reciprocal polarizers 17,18 thereby enabling a conventional variable phase shifter 62 to be employed therebetween. As before, transducers 64,65 are employed to provide input-output connections to the device. Circulators 60,61 are defined as having three ports designated A, B and C. In one state, an input to port A is emitted from port B, an input to port B is emitted from port C and an input to port C is emitted from port A. In an opposite states an input to port A is emitted from port C, an input to port C is emitted from port B and an input to port B is emitted from port A. Referring to FIG. 7, port B of circulators 60,61 are connected to opposite extremities of variable phase shifter 62. Transducer 64 resolves input energy into first and second orthogonal components available at terminals 67,68, respectively, which are connected, respectively, to port A of switchable circulators 60,61. Transducer 65 is adapted to combine the first and second orthogonal components applied at terminals 69,70, respectively, which are connected to port C of switchable circulators 61,60 respectively. Means for switching the circulators 60,61 is not shown.
In the operation of the device of FIG. 7 to transmit from left to right, as viewed in the drawing, the circulators 60,61 are switched to operate in a counterclockwise direction as indicated by the arrows. Thus, first and second orthogonal components from transducer 64 are applied to port A of switchable circulators 60,61, respectively, and emanate from port B thereof and propagate in opposite directions through variable phase shifter 62 whereby each wave is delayed by φ 1 . The energy delayed by φ 1 is applied to port B of the opposite circulator 60 or 61 from whence it is emitted from port C thereof and applied to terminals 69,70 of transducer 65. Transducer 65 combines the delayed orthogonal component whence the input wave delayed in phase by φ 1 is emitted from the output thereof. To reverse the direction of operation from right to left, as viewed in the drawing, the switchable circulators 60,61 are both switched to effect a flow of energy in the clockwise direction. Operation is the same as before.