US2907959A - Finline phase shifter - Google Patents

Description

Oct. 6, 1959 s. D. ROBERTSON 2,907,959

FINLINE PHASE SHIFTER Filed May 21, 195s s Sheets-Sheet 1 v uvvs/v TOP 2 By 5.0. ROBERTSON ATTORNEY Oct. 6, 1959 Filed May 21, 1956 S. D. ROBERTSON FINLINE PHASE SHIFTER 5 Sheets-Sheet 2 //v vavron By S. 0. ROBERTSON ATTORNEY Oct. 6, 1959 's. D. ROBERTSON FINLINE PHASE SHIFTER s Sheets-Sheet 3 Filed May 21, 1956 FIG. 6

VENTOR s. 0. IQOBERTSO/V ATTORNEY.

United States Patent 'This applicationis; a continuation-impart of. my co pending applicationSerial No. 485,671=filed February 2,

1955, and this invention relates. to coupling. arrangements for use in signal wave transmission, and. more particularly to such coupling arrangements ofthe so-called differential phase shift variety.

A signal wave propagatingalong .a transmission path, such as a circular hollow :wave guide, maybe viewed as. comprising two mutually perpendicular components, for example a vertical and a horizontal component. Various techniques have been proposed for shifting the qphase of one of these components with respect .to the other, for certain well known purposes to be discussed hereinafter. Coupling arrangements, for achieving this have. been called:difi'erential-phase shifters ordelta sections. The .most useful. phase shifters. of this type are those which introduce a phase differenceof 90,degr ees or 180 degrees, so-called delta 90.degree or delta ;18Q,-degr ee sections.

The differential phase shifters proposed heretofore operate .to separate-the two. components of awave so that they-propagate for a time alongdiiferentpaths. Then they are recombined. The electricaLlengths i .e., the distances-measured in radians of the propagatingwave) of the two paths areadjusted to be different. so-that, at recombination, one component of thewave is retarded with respect to the; other. Disadvantageously,; thephase shifters proposed heretofore are not broad band devices .since the electricallengths of'their two.- wave paths vary -'.ditferently withfrequency. --jHeguce -the diiferer cedn their electrical lengths cannot readily bernaintained constant as, the frequency. varies.

Accordingly, a principal object; ofithe presentinvention :is to achieve. arbroadband differential phaseshifter.

A further object is to provide a differential phase :shifter that is flexible in nature and so can be readily adapted for awide'variety of circuit applications.

' In acoordancewith the present inventiomthere is pro- -vided a .ditferentiahphase shifting arrangement which comprises a-first pair of-finlines which are disposedin :mutually perpendicular planes along one region of the signal. wave path, a second pair, offinlines which are also disposed inmutually-perpendicular.planes along a differ- :ent regionof the signalwave path, and a pair of wave- .guiding members Whose electrical lengths differ by. apre- -determined..amo.unt, the difference beingsachieved in a manner which isindependent of frequency, each interconnecting .onefinline ofthefirst; pair-.with a' finline of the second pair. Each ofthe finlines comprises ,two thin 'coplanar. conductive fins having thicknesses no more than .;several .percent. of a-wavelengthat the cut-off frequency ofthe wave .guide.

The two:fins ,of eachfinline .are spaced, apart along; their, entire. lengthand .the space between.them, forms amwavepath bounded\.by their opposing edges. .Ihetransverse dimension of thepath ,thus formed -isextremelysrnall over. the central portion of .its. length. and .is tapered: at least-at .one. endfor :matching -,the .characteristic; impedance .of that .central ..quen cy,in;the same fashion. and sothe difference intheir waveguide. Pinlines of this type are also disclosed in a copending application Serial No. 485,672 off-1LT. Friis and S. D.-Robertson, filed February 2, 1955.

Differential phase shifters have been proposed heretofore employing a single finline, rather than one or more pairs of finlines, but such phase shifters have not been broad band devices. Such phase shifters provide two paths of different electrical lengths for the two mutually perpendicular components of a wave. Butthe electrical lengths of those two paths vary differently with changes in frequency, and so it-is diflicult to maintain the difference in their lengths constant over a. broad; frequency band. Moreover, couplers using only one finline are not characterized by the -flexibility that is exhibited by the differential phaseishifters of the present invention,

In one embodiment, the. present invention comprises .first and. second sections of hollow conductive wave guide, apairof finlines extending along mutually perpendicular. axial planes within each of the wave guides, and a pair .of waveguidingmembers each interconnecting one finline of thefirst. wave guidesection with onefin'line'of the. secondv wave .guide, section. There is thus fo'rnied a separate continuous wave .path between the two wave guidesections .for each of two mutually perpendicular components of.a wave propagating along the first section of wave guide. Any desired difference 'in phasels h ift between :the two components can be achieved by adjusting the two wave paths to have different electrical lengths.

In the preferred embodiment of .theinvention, the two wave paths providedare similarphysically except that in onethere is introduced a phase shift that'is independent of: frequency, .such as .is. achievedby interchanging ,the two elements of a parallel pair transmission line. Hence the electrical lengths. of-"the two paths vary with'freelectrical lengths remains constant over a widefre'quency band.

'[he.invention. will be explainedin greater. detailinthe followingtdescription taken in conjunction with the, accompanyingdrawingin which:

E l a pe sp ctive view of one .embodiment of the present invention forming a-ditferential phaseshifter between two s paratesections, of hollow wave guide;

Fig lA is a longi udinal sectional view 'of afinline coupling element of the type used in. the differential phase shifter of Fig, 1;

Fig. 2. is a perspective :Yiew of. asecond embodiment of the present, invention forminga-dtferential phase shifter in av straightthroughwave guide;

'EigS. -3, 3A, 3B, and- 3C are modifications of the-differential, phase shifter. of Fig. 2;

v Fig. 4is a further modification of the differential phase shifter of Fig.- 2, for use as acirculator;

Fig. 4A is a schematic representation of a circulator shown for purposes of explanation; and i Figs. 5 and 6 .show examples of a third embodiment of the present invention forming reflex-type. differential phase shifters. V

Referring now. more particularly to the variousfigures of the drawing, Fig. 1' discloses a differential-phase shifter 10 comprising first .andsecond sections 11 and 12 of hollow :o n ductive wave guide which are interconnected "by coaxialv lines 13 and. 14. Coaxial line 13 forms a wayeguiding path between; finlines 15 and,16, and coaxia1 dine. 14 forms a waveguiding Pathbetween .finlines 17 and 1's.

1 For.expositionpurposes. finline 15 is; shown. in greater .detailin Fig. 1A. .Inthisfigure the finlineco'mp'rises two fins.-15A-and;15B ;which extend in an axial plane within waveguide 11. The two fins are spaced apart along' their entire; length f0r; forming .,therebetween. a

continuous wave path 15C bounded by the opposing fin edges. The transverse dimension of this finline path initially equals the transverse dimension of wave guide 11, then tapers gradually to a smaller dimension along an intermediate portion of its length, and finally tapers gradually to the transverse dimension of coaxial line 13. The smaller dimensioned intermediate portion of wave path 15C advantageously extends outside the wall of wave guide 11 so that the propagating wave energy is closely confined during traversal through the wave guide wall and hence is not seriously affected by any discontinuity presented by that wall.

In the operation of the finline coupler of Fig. 1A, a wave propagating from left to right along wave guide 11 whose electric field vector is polarized in the plane of finline 15 will pass along the finline wave path 1 C to coaxial line 13. Contrariwise, a wave polarized perpendicular to the finline will continue along the wave guide substantially undisturbed by the presence of the finline, as the finline presents an equipotential surface to a wave so polarized. To ensure undisturbed transmission of the perpendicularly polarized wave, the thickness of the fins should be less than one-tenth the guide diameter and preferably approximately one-sixty-fourth of the guide diameter. These dimensions correspond to four percent and less than one percent, respectively, of the cut-off wavelength of the guide. A more detailed discussion of the finlines can be found in my aforementioned copending application and in my copending application Serial No. 549,734, filed November 29, 1955.

Returning now to Fig. l, a wave propagating from left to right along Wave guide ll may be viewed as comprising two mutually perpendicular components, one in the plane of finline 15 and one in the plane of finline 17. These have been shown in the figure as vectors E and E The component represented by vector E passes from wave guide 11 along finline l5, coaxial line 13, and finline 16, into wave guide There it appears as E The component represented by vector E continues undisturbed past finline l5 and passes from wave guide ll along finline l7, coaxial line 14, and finline 18, into wave guide 12 as vector E It should be noted that E lags E by 90 degrees in space but E leads E by 90 degrees in space. Thus a 180 degree phase shift in space, which is equivalent to a 180 degree phase shift in time, is effected between the components. Accordingly, the cou pling arrangement serves as a delta 180 degree section. Additionally, the coupling arrangement provides a convenient technique for circumventing a bend from circular wave guide section 11 to section 12 without the generation of spurious modes.

It will be observed from Fig. 1 that the wave path of each of the two components E and E after their separation and before recombination, consists of a section of hollow wave guide, two finlines, and a section of coaxial line. If the electrical lengths of the corresponding elements of the two paths are made equal, the length of the two paths will remain equal independent of frequency. Hence the phase shift between the two components will remain constant at lSO degrees independent of frequency.

A second embodiment of the present invention for forming a differential phase shifter 29 in a straight through guide is shown in Fig. 2. In this embodiment a wave propagating from left to right along a hollow conductive wave guide 2;. is again viewed as comprising two mutually perpendicular components, represented by vectors E and E Component E lies in the plane of finline 22, which plane will be referred to as a vertical plane, and so is coupled thereby out through the wall of the wave guide to a closely spaced two-conductor line 23, which is shown as an extension of the finline, and then back through the wave guide wall in finline 24- in a horizontal plane. There it appears as vector E Component E on the other hand, lies in the plane of finline 25, and so is coupled thereby to two-conductor line 26,

,K shift is provided by element 38 two-conductor line 36.

then to finline 27, and finally appears as vector E at the right-hand end of wave guide 21. As shown by these vectors, E lags E by degrees in space but E leads E by 90 degrees in space; thus a degree phase shift in space, and hence in time, is effected between the two wave components. The operation of the finlines in this embodiment is similar to that of the finlines in Fig. 1. Here, as in Fig. 1, the spacing between the two fins of the finline should be extremely small at the point where the fins pass through the conductive wave guide wall.

It will be noted that the 180 degree differential phase shifter 20 of Fig. 2 may be employed as a rotary joint. In particular, if E represents a wave rather than a component of a wave and its polarity is rotated in a counterclockwise direction, it will be observed that it will appear the right-hand end of the phase shifter 2%) as E having a polarity which rotates in a clockwise direction. Thus it can be appreciated that, if the polarization of wave E is maintained constant but the differential phase shifter 21B is rotated, the polarity of wave E will rotate in a direction opposite to the direction of rotation of the phase shifter and at a speed twice the speed of rotation of the phase shifter. A wave guide coupling arrangement which is characterized by operation of this type is commonly referred to as a rotary joint. It finds particular application in a wave guide transmission path coupled to a rotating or scanning antenna.

Fig. 3 shows a modification of the difierential phase shifter of Fig. 2. in this modification, unlike that of Fig. 2, the two finlines 32 and 34 which are joined by two-conductor line 33 are coplanar. Further, finlines 35 and 37 joined by two-conductor line 36 are likewise coplanar. Component E of this modification traverses from left to right through the differential phase shifter 38 without a change in phase, and appears as IE Component E however, experiences a 180 degree phase shift in traversing from left to right through the differential phase shifter and appears as E The 180 degree phase shown schematically in Various techniques for providing the 180 degree phase shift are shown in Figs. 3A to 3C. These figures show portions of a coupling arrangement similar to Fig. 3. Elements of these figures which correspond to those of Fig. 3 have been given similar reference numbers.

In Fig. 3A the 180 degree phase shift in the twoconductor line 36 is provided by a semi-circular rotation 38A of the path.

In Fig. 3B the 180 degree phase shift is provided by a twist 383 in the path, i.e., the interchange of the relative positions of the two elements defining the wave guiding path.

Finally, in Fig. 3C the phase shift is provided by a section of ferrite material 38C positioned within rectangular wave guide section 3? which is connected be tween the tapered fins 36a and 36b to form a part of wave path 36. The ferrite material is in the form of a rectangular slab which extends in the direction of, but displaced laterally from, the axis of the wave guide. Arrangements of this type are disclosed in an article entit ed Behavior and Applications of Ferrites in the Microwave Region by A. G. Fox, S. E. Miller and M. T. Weiss appearing in vol. 34 of the Bell System Technical Journal, January, 1955. In operation a magnetic field H is provided for magnetically biasing the ferrite material in the direction shown by the arrow in the figure. it is characteristic of this material when suitably magnetically biased that it exhibits a unidirectional or nonreciprocal phase shift, that is, it imparts a substantial phase shift to a Wave passing through it in one direction but imparts virtually zero phase shift to a wave passing through it in the opposite direction. In the instant case, the length and properties of ferrite material 33C are selected to provide in the presence of magnetic field H a phase shift of 180 vdegrees in one direction and virtually'zero inthe opposite direction. As-aresult, of

this, the resulting differential, phase. shifter, '3 0. would likewise be nonreciprocal in..natu.re,.that is, .there\.would be 180'degree differential phaseshift action from left to right but no differential .phaseshift .actionfrom right to left. However, if.reciprocal-differential phaseshift action is desired, av rectangular waveguide; including a second section. -of ferrite material characterizednby 180 .,degree phase shift for a wave. passing. from right to.-. left can-beinserted in either path 36 or path'33. Additio n- .ally, nonreciprocal or reciprocal dilferential phase shift of any other desired angle, for-example90 degrees, can behhad by suitably choosing one'or-two ferritehsections to: give. the desired phase shift. Othenarrangements, can

be devised for particular applications,for-example a -dif-: .ferential phase: shifter-cambewbuilt .having a-90 degree nonreciprocal phase Shift-11130116 path and a 180 degree nonreciprocal phase shiftin the other. path.

It. should. benoted-that ferrite section-38 C;acts toidfelay the. phase. of va wave passing;therethrollgh with respect -to..the; phase of, a wave passsingythrough; path,:33. :In

this manner. a differential phase. shiftzin time between :the

. two components E .and E is; achieved. .aBut disadvantageously the time delay provided by the. ferrite doesg not remain constant with frequency; and .so .its. effective frequency range is limited. On the. other hand, phase shiftsections 38A and 38B do. not.act..as time delays fora wave component passing through, but rather they provide .a spatial. phase shift. of: 18.0.degrees :and. this phase shift advantageously is independent offrequency so long as the corresponding elements :of the. wave paths for the two components. of the. wave arev made to be similar physically.

Fig. 4 shows a modification of the diiferential phase shifter of Fig.2 for forming a circulator. thisfigure which correspond to elements described with reference to Fig. 2 have been given like reference numerals and will not be redescribed here. -In-this modification rectangular wave guidesectiom 41 including ferritematerial 42 is located-inpath 26. Thisferritemember -is advantageously chosen to provide, in the presence of magnetic field H, a. 180 degree phase shift-for a wave passing therethrough from left to right and approximately zero phase shift for-a wave passing fromright to left.

'.In this case, a wavewhose electric fieldis polarized-as -'vector'E which is at an-angle of-45 degrees-witheach of finlines 22 and 25 will bedivided-in'half. Onehalf "will-pass alongfinline 22,- two-conductor line 23,-and -finline 24, and the other'half will pass along finline"25, two-conductor line 26- and finline 27, the phase of- 'this latter half being shifted 180degrees-by ferrite member The two halves are then recombined-atthe righthand end of wave guide 21 and they appear asvector E But a .vector appearing as E, and traveling from right to left will be divided in half, the two halves traversing thetwo finline wave paths and recombining at'the lefthand end of wave guide'21 as vector E Further E passing fromleft to right through the"difierentialphase shifter 40, separates into halves and then recombines at the right-hand end as vector E and awave represented by vector E passing from right to left, separates into halves and then recombines as E,,. This actionycan' be illustrated by the schematic representation shown in Fig.- 4A. The arrow 45 indicates the direction of wave energy flow between adjacent terminals-of the circulator. Thus wave energy E flows .to E E to.E ,"E to' E and E to E For use as a circulator, finline elements, such as'shown in Fig. 1A, are advantageously employed for launching the linearly polarized waves in the. desired polarity, for example in the polarity of E and for.selectively extracting the wave energy from the ends of wave guide 21. on

the basis of its polarity.

Fig; shows a third embodiment of the present inven-.

Elements of" tion. formi g .a. reflexrtypeadifterential phase shifter 501 This embodimen comprisesahollow wave guide/.51, .and two'fin inesfizand. .4..ioinedbya tw -conductor l n v5 ,Ihe tw.o jfinlines extend .ialOng ..mutually perpendicular .aXial..p1.anes.Wi hin the. hollow waveg id .IIL p tion, w vecqmnonentent r ng asvec r E1. at th l fthan cinder. waveguide ,51. passes .along ,finline 52,v twoconduct r.. n .ifin .n ..54, and ,.is reflect das e r Ezmi1an y,. ..wavec mpon n n er s. vector E passes alongfinline54, two-conductor.-.line.53,.and fin i 5. n irefl ctedtas vector. 31- Thusth w components ,of the wave .arewdiiferentially .-phase ,shifted 180 degree,.-. as. E .acquiresa 0, .degreelag, and E acqu r .a 9 de re lead.

Observing .the direction .of;..p.hase shift acquired .by these components, it can be seen that if E represents ,a wave, ratherL than ,only a ,.componenti,of,a wave, and

po r za i n. i rotated. inane. direction, for ex p clockwise, the polarization ofthe. reflectedwavewill. ro-

late, in the Opposite. direction or counterclockwise. 'Ad- .ditiona'lly, if the polarization, of-..waye. E is. maintained constant, but the differential phase shifter 5 0..is rotated, then the polarity-ofthe refiected..wave.willrotate in a direction opposite to thedirectionof rotation of the .phase shifter andat a speedtwicethe ,spcedof-rotation .of the ph se shifte Eig- 6 shows a, reflex-type .di fierential phasev shifter 60 .which is a modification of the one shown in Fig.5. This phaseshifter differs, frormthe. one in. Fig. .5 bin. that. it includesin the. tWQrQQnductor line. 53.. a .rectangularzwave guidesection 6]. having ,thereina slab of ferrite material 62. 'This ferrite member is advantageously, chosen to provide, in the-presence .of magnetic .field. H, a phase shift of degrees in ,one direction .and. approximately zero.in the. other..f.or effecting .a 90. degree. differential phase shifter. .lnsinchflawcase, awave inserted at the left-hand end as, yector. E ,..-which. is. 45 degrees from the ,plane of eaclrofethe filllines .52, and,,54,-. will. be divided in half. Qne ,half. will; ,pass ,first. along. .finline: 52, then two-conduQtOL .li le..53,, and .then: finline..5 4, and the .other half willpass first; alongifinline 54; then two-conductor 'line153, ,and, then.,fin1ine, 52. Only-one ofthese-halves will be phase shifted 90,.degrees by. fenritezsection-61; and

. so they will, recombine. with. a .,difierential"phase shift-of 90 degrees. Such a 90 degree differential phase shift-is known-totransfonn a linearlypolarized .wave into a-- circularly polarizedwave. Accordingly, a wave entering. the

diiferential phase ,shifter..60. linearly polarized as. vector E will be reflected, as.v a circularly polarized .wave.

. It is understood. that ,theforegoing specific embodiments are merely illustrative. of the general prinoiples...of the present invention. In the .lightsof..these embodirnents,

. when a particular phaseshift. is desired, for. example. of

90: degrees, it is notessentialthat :one, pathv provide 7 a. 90 degree delay andthe. other. a...zero d e.lay. Rather,- it.is

P i e-to makethe ,delay .inone; pathanyphysically realizable value and merely, have the del-ayof the other 1 path differ-by- 90 degrees. With .such an arrangement any change in electricallength with-frequency of .onepath might advantageouslybecompensated by a .changein electrical length ,of the. otherp-ath and .thusthe. difference in electricallength maintained constant over. a..-broa.der

. frequen y. band.

..What. is Qclaimedis:

1 .;.,A differential, phase-shifter comprising; first 1and.-sec

.ond sections. .ofhollow, conductive wave guide firstzand second, pairs of finlines extending axially. within said first and second wave guide sections, respectively, the two finlines of each pair being positioned in mutually perpendicular planes within the respective wave guide sections and extending out through the conductive wall of the respective wave guide sections, each one of said finlines comprising two conductive fin elements spaced apart along their entire length for forming along the interspace therebetween a continuous wave path bounded by opposing fin element edges, the transverse dimension of said con tinuous path initially being equal to the transverse dimension of the respective sections of hollow wave guide, then being tapered therefrom to a smaller dimension for passage out through the conductive wall of the wave guide section. and waveguiding means for coupling each finline of the first pair exclusively with a different finline of the second pair.

2. The combination of elements set forth in claim 1 wherein said waveguiding means comprises a pair of twoconductor transmission lines.

3. The combination of elements set forth in claim 1 wherein said waveguiding means comprises a pair of coaxial lines.

4. A coupling arrangement comprising first and second sections of hollow conductive wave guide, the axis of the first wave guide section being displaced from that of the second, first and second pairs of finlines extending axially within said first and second hollow wave guide sections. respectively, the two finlines of each pair being located in mutually perpendicular planes within the respective wave guide sections. and waveguiding means for coupling each finline of the first pair exclusively to a different finline of the second pair.

5. A coupling arrangement comprising first and secnd sections of hollow conductive wave guide. the axis of said first hollow conductive wave guide section is aligned with said second hollow conductive wave guide section and the two sections are joined to form com ponent parts of a continuous wave guide, first and second pairs of finlines extending axially within said first and second hollow wave guide sections, respectively, the two fin ines of each pair being located in mutually perpendicular planes within the respective wave guide sections, and waveguiding means for coupling each finline of the first pair exclusively to a different finline of the second pair.

6. A differential phase shifter comprising first and second sections of hollow conductive wave guide, a first pair of finlines extending along mutually perpendicular axial planes within the first section of hollow wave guide, each finline being responsive to one of two mutually perpendicular components of a wave propagating along said first hollow conductive wave uide, a second pair of finlines extending along mutually perpendicular planes within the second section of hollow Wave guide, means forming a first continuous path between said first and second hollow Wave guide sections including a first waveguiding means in energy transfer relation exclusively with one finline of each of said finline pairs, means forming a second continuous path between said first and second wave guide sections including a second Waveguiding means in energy transfer relation with the second finline of each of said finline pairs, the electrical phase shift of one of said continuous paths being different from that of the other for effecting a differential phase shift between the two components of said propagating wave.

7. The combination of elements set forth in claim 6 wherein the differential phase shift between the two components of the propagating wave is provided by a section of ferrite material located in one of said continuous paths between said first and second wave guide sections.

8. A differential phase shifter comprising first and second sections of hollow conductive wave guide, a first pair of finlines extending along mutually perpendicular axial planes within the first hollow wave guide, each finline of which is responsive to one of two mutually perpendicular components of a wave propagating along said first hollow conductive wave guide, a second pair of finlines extending along mutually perpendicular planes within the second hollow wave guide, means forming a first continuous path between said first and second hollow wave guide sections including a first waveguiding means in energy transfer relation exclusively with one finline of each of said finline pairs, means forming a second continuous path between said first and second wave guide sections including a second waveguiding means in energy transfer relation with the second finline of each of said finline pairs, said first waveguiding means being adjusted to follow a substantially semicircular path for providing a degree differential phase shift between the two components of the propagating wave.

9. A differential phase shifter comprising first and second sections of hollow conductive wave guide, a first pair of finlines extending along mutually perpendicular axial planes within the first hollow wave guide, each of which is responsive to one of two mutually perpendicular components of a wave propagating aiong said first follow conductive wave guide, a second pair of finlines extending along mutually perpendicular planes within the second hollow wave guide, means forming a first continuous path between said first and second hollow wave guide sections including a first wave-guiding means in energy transfer relation with one finline of each of said finline pairs, means forming a second continuous path between said first and second wave guide sections including a second waveguiding means in energy transfer relation with the second finline of each of said finline pairs, one of said waveguiding means being twisted substantially 180 degrees for providing a 180 degree differential phase shift in the components of the propagating wave.

10. A differential phase shifter comprising first and second sections of hollow conductive wave guide, a first pair of finlines extending along mutually perpendicular axial planes within the first hollow wave guide, each of which is responsive to one of two mutually perpendicular components of a wave propagating along said first hollow conductive wave guide, a second pair of finlines extending along mutually perpendicular planes within the second hollow wave guide, means forming a first continuous path between said first and second hollow wave guide sections including a first wave-guiding means in energy transfer relation with one finline of each of said finline pairs, means forming a second continuous path between said first and second wave guide sections including a second waveguiding means in energy transfer relation with the second finline of each of said finline pairs, the path of both of said waveguiding means being twisted and the sum of the magnitudes of their twists being equal to 180 degrees for providing a 180 degree differential phase shift in the components of the propagating wave.

11. The combination of elements set forth in claim 10 wherein one of the waveguiding paths includes a section of ferrite material for providing a further differential phase shift between the two components of the propagating wave.

12. The combination of elements set forth in claim 10 wherein one of the waveguiding means includes a section of ferrite material for effecting a 180 degree phase shift in a wave propagating therethrough whereby circulator action is achieved.

13. A coupling arrangement comprising means forming a waveguiding path, four finlines longitudinally spaced in a succession within said waveguiding path, the first and second finlines in the succession being disposed in mutually perpendicular axial planes and the third and fourth finlines in the succession likewise being dispose in mutually perpendicular planes, means forming a continuous wave path exclusively between the first and third finlines in the succession including a first transmission line in energy transfer relation with said first and third finlines, and means forming a continuous wave path beg tween the second and fourth finlines in the succession including a second transmission line in energy transfer relation with said second and fourth finlines.'

14. A differential phase shifter comprising a hollow conductive wave guide, a pair of finlines extending along mutually perpendicular planes within the hollow conductive wave guide, means forming a continuous wave path between said finlines including a transmission line independent of said hollow conductive wave guide connected in energy coupling relation between said finlines.

15. The combination of elements set forth in claim 14wherein the transmission line comprises a parallel two-conductor transmission line.

16. The combination of elements set forth in claim 14 including means located in said continuous wave path for providing a nonreciprocal phase shift for a wave propagating along said continuous path.

17. The combination of elements set forth in claim 16 wherein the phase shift means comprises a section of ferrite material characterized in that it provides a 90 20 2,691,731

degree phase shift in one direction and substantially zero phase shift in the other direction.

18. A coupling arrangement comprising first and second sections of hollow conductive wave guide, an axially extending finline within said first section supporting energy applied with polarization in a predetermined quadrant, an axially extending finline within said second section, and transmission means independent of said hollow conductive wave guide sections connected in energy coupling relation between said finlines, said transmission means introducing a rotation of the plane of polarization such that said finline within said second section launches energy into said wave guide polarized in a quadrant other than said predetermined quadrant.

References Cited in the file of this patent UNITED STATES PATENTS Fox June 22, 1948 Zaleski Feb. 10, 1953 Miller Oct. 12, 1954

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