US2945193A

US2945193A - Rotary waveguide joint and switching structure

Info

Publication number: US2945193A
Application number: US407685A
Authority: US
Inventors: Leland D Strom
Original assignee: Texas Instruments Inc
Current assignee: Texas Instruments Inc
Priority date: 1954-02-02
Filing date: 1954-02-02
Publication date: 1960-07-12
Anticipated expiration: 1977-07-12

Description

L. D. STROM 2,945,193

AND SWITCHING STRUCTURE Jul 12, 1960 ROTARY WAVEGUIDE JOINT 5 Sheets-Sheet 1 Filed. Feb. 2. 1954 INVENTOR.

- lzL/i/voflSmo/vr x 46 mzwwww ATTORNEYS July 12, 1960 1.. n. STROM ROTARY WAVEGUIDE JOINT AND SWITCHING STRUCTURE Filed Feb. 2. 1954 5 Sheets-Sheet 2 W7 W8 a 0 W. k

WWW

Arro/e/vgvs L. D. STROM 2,945,193

ROTARY WAVEGUIDE JOINT AND SWITCHING STRUCTURE July 12, 1960 5 Sheets-Sheet 3 Filed Feb. 2. 1954 INVENTOR. LELfl/Vfl D. STROM A TTORNEYS L. D, STROM 2,945,193

ROTARY WAVEGUIDE JOINT AND SWITCHING STRUCTURE July 12, 1960 5 Sheets-Sheet 4 Filed Feb. 2. 1954 INVENTOR. LEAH/v0 Q STROM ATTOEMFYS 1.. D. STROM 2,945,193

ROTARY WAVEGUIDE JOINT AND SWITCHING STRUCTURE July 12, 1960 5 Sheets-Sheet 5 Filed Feb. 2. 1954 INVEN TOR. ZnA/vo J'TAOM A TTOE/VE vs tes ROTARY WAVEGUIDE worm AND SWITCHING STRUCTURE T Leland D; Strom, Dallas, Dallas County, Tex., assignor to Texas Instruments Incorporated, Dallas, Tex, acorporation'of Delaware Filed'Feb: 2, 1954, Ser. No, 407,635

17 Claims. (Cl. '333-.-7)

This. invention relates to. a rotary jointand switching structure. and morev specifically, to. a rotary joint, of. the

rectangular waveguide. type so constructed as to transfer R.-F.. power.t0 an antennarotatingthrough360 degrees, or to switch R.-F. power alternately to morelthanone antenna vfeed while maintaining. 3.60degrees rotation-of the antenna :array...

It will be appreciated that rotary waveguide joints .as such .are not new- Prior art joints have beendeveloped using the circularTM mode andithe rectangularuTE mode. One of thislatter type of joints wasadisc losed in a NavalResearch Laboratory Report in 1951 by Breetz and embodied in Patent.No. 2,595,.l-.86 issued April 29, 1952,10: Breet zQ Therotary joint in the referred to. report consists :of a. rectangular waveguide sbent in the -E-plane :to form a complete circler with the waveguidesplit along the narrow wall to permit relative motionflbetween the respective: sections. Waveguides-iconnected into the opposite and facing wide sides of the waveguide sections form 'the power input-and output for the joint with the input guideconnected to the inner section and. the output guideqto the outer section. At the junction points of the input and output guides to their respective sections of the circular guide are sets of fingers. extending into the guide and directed at such an angle as to make E-plane bends for the feed to and from the rotary joint. The fingersinzthe E-plane bend are set at approximatelya 45 degreerangle with .the tangentto the circumference of the circle where-the fingers enter the ring and serve to'jdirect the pathpf the wave fr-om the input guide through the rotary joint and-to the output guide. These fingers attaehedto the relativelyrotating Sections are arranged to interleave thus permitting 360-degree rotation.'- p

Although it is'essential to direct the path. of the input wa e yet it is-undesirable for several reasonsrtor direct the wave pathwby using sets of interleavingfingers. Ihfe practieal difiiculty of fixing the fingers to the input and output isect-ions because of the :relatively small dimensions: of the waveguide constitutes a disadvantage of this-apparatus. Further, :the difficulty ,in setting" the arcing takes place causing undesirable zrefiections. into the input arm.- This necessarily means'that when fingers 'areused to direct the path of the wave from 'the input guide to the output guide, the rotaryjointissinherently limited to a 'low' amount ofipower that can .be transferred through the joint. 1 Accordingly it is aprincipal object of this invention to' provideqan apparatus' that willavoid the low power I traiisfer limitat-ions .of previously-known rotarynwavee guide-jointsuby utilizing. devices -:.which have directional A 2,945,193 Pa en ed July 969 2 characteristics of themselves without. the necessitylof using power limiting devices such as interleaving fingers to accomplish wave path directivity. It is another object of this invention to provide an apparatus that willavoid construction difiiculties present with prior devices and one which will be simpler and more easily constructed.

It is a further object of this invention to provide structure .which can be easily adapted for switching the input power between two or moreantennas. s

It is still another object of this invention to proyide a small, compact structure suitable for stackingonejoint upon another with colinear axes of rotation for feeding an array of antennas without interference betweenthe various feed arms to the antennas.

Other and further objects of the invention aswell as the characteristics of the structure necessary to accomplish the above enumerated'objects will become. apparent from the following discussion For thispurpose the discussion is referenceduto the following .drawingsai n which:

Figure 1 is a partially broken-away perspectiveview of the preferred embodimentof. the invention showing a directional-coupler. as the directivedevicer. 1

Figure, 2 is avcross-sectionalqview.of Figure intake]; in a radial plane .passing,symmetrieallythro l h the device showing the .wave path ...as directed by the :inputsaud output directional couplers;.. I l Figure i, is 'al view similar to Figure 2il-lustrating wave paths at the cross-over positien;..

Figure 4 is a perspectiveview partially. broken away showing. .the use .of hydridtTs as, a modification .ofthe invention;

Figure 5 is a cross-sectional view of Figure4-takenin a radial plane .passing symmetrically. through the (if/Vice illustrating the wave path around-the rotary jointrtoarthe E-arm of the hybrid T;

Figure 6 is aperspecti-ve view of the device show-nip Figure 4 showing the wave paths into the E andH-arngs of the hybrid T at the cross-over point;

Figure '7; is a partially broken-away perspective-vie w of a directional coupler switching arrangement according to another modification of the invention; 1

Figure 8 is a cross-sectional view of Figure 7 takenrin a radial plane .passing symmetrically through the device;

Figure 9 is a perspective view of a hybrid' lswitching arrangement according to a further embodiment ;of the invention; and

Figure 10 is a cross-sectional view'of FigurerQQ-taken in a radial plane passing symmetrically nthrough the device. 7

Referring now to the various figures, it:.can:be seen that the basiestructure, of the rotary jointis-identical for all embodiments ,of the present inventionuwithwthe dilferences between the several embodiments beingsinathe means for accomplishing wave pathsdirectivity. IBasi-i cally, the rotary jointgconsists of arotor-20 and-astatoli 21. Rotor -20 is a cylindrical annulus in shape with a raised area around its mid-portionwhich .forrns three sides of a waveguide :24. '1 The; wide .side .of waveguide 24 is designated by the number 22-and the marrowsides by the number 23, all an integral part-of rotor 20. The closure of waveguide 24 is effected by the side wall of stator 21 when the stator is in rposition within rotor 20. Stator 21 is also a cylindrical annular structure, however, it is further formed with-two inwardly extending circular annular sections 26 and..28 located toward the upper and lower vends .of the stator 21 respectively: slot .25 is cut into section 26 to a .depth equal to a quarter wave length at theaoperatinglfrequency' of the system and is connectedwith the mainguide: 24 bymeans of-another quarter 'wave length passage 34a formed between the rotor and stator. Thus, slot 25 is located at a quarter wave length above waveguide 24 and acts as a choke to prevent the loss of R.-F.- power.

Fro'm transmission line theory, the voltage is amaxiand the current is essentially zero at a point located at. a quarter wave length from a short circuit in a transmission line. Consequently, an impedance approaching infinity is possible 'at the junction of

slots

25 and 34a. This high impedance is in turn transformed through a quarter wave length section 34a, resulting in an effective short' circuit at the junction of slot 34a and waveguide 24. 'It should be recognized that passage 34a is formed as a result of reducing the diameter of stator 21 to avoid metal-to-metal contact with rotor and is as narrow as possible. In like manner, a quarter wave length slot 27 is formed in the lower section 28 and is connected by quarter wave length passage 34b with the lower side of waveguide 24. r a

Although not shown, it is necessary for the stator and rotor sections to be maintained in their relative positions by means of a suitable bearing arrangement. This can be accomplished by using stator 21 as the inner race and attaching cover plates to either end of rotor 20 to serve as the outer races of a ball bearing movement. The rotary joint is not restricted to the above designation of rotor and stator sections because the construction of the joint allows either to be used as the rotating 7 or; stationary section. Further, if the rotary joint is to be used in a pressurized system, '0 seal rings can be provided for this purpose. Sealing means is shown in Figure 1 and consists of 0 seal ring 38 in groove 29 and '0 seal ring 32 in groove 31, located at the upper and lower ends of stator 21 respectively.

7 In the operation of the embodiment shown in Figure 1, wave path directivity is accomplished by means of directional couplers. The R.-F. power is fed from input guide 33- into a directional coupler 35, which fits into an opening provided in the side wall of stator 21. Two mutually

perpendicular slots

36 and 37 are formed into the wall of directional coupler 35 facing the circular waveguide 24. These

slots

36 and 37 are each resonant at the operating frequency of the system and, consequently, tend to effect practically a 100 percent transfer of power from the coupler into the waveguide 24. A,

high-dielectric strength plug 38 that does not materially raiuce the transfer of power is inserted into the opening provided by the mutually

perpendicular slots

36 and 37. It may be desirable also to insert a plug of highly absorbent material, connnonly termed lossy material in the art, into directional coupler 35 at the terminal indicated by the numeral 48.

- A directional coupler 42 is fixed to an opening cut into the wide face 22 of the circular waveguide 24 and serves as the power output from the rotary joint. Directional coupler 42 has two mutually

perpendicular slots

39 and 40 filled with a high dielectric strength plug 41 in the samemanner as directional coupler 35. It can pled into the waveguide 24 where it travels in the direction indicated by path 45 as the preferred direction until it reaches the

coupling slots

39 and 40 in directional coupler 42.

Slots

39 and 40 directionally couple the wave into coupler 42 where the wave takes the path indicated by numeral 46 to the outlet 43 of the coupler.

It is obvious that if there is relative movement between rotor 20 and stator 21, path, 45 will change in length until the

slots

36 and 37 have rotated relatively to a

point directlyopposite slots

39 and 40 as shown in Fig, ure 3. This varying path length makes no difference until the slots in the two couplers are directly opposite and reach what is termed the cross-over point. When this point is reached, the R.-F. power splits and a portion follows path 45 around the circumference of the ring joint while a portion follows path 47 directly across to directional coupler 42 and recombines with the wave following the path 45. In order to avoid a recombinaflected waves can be minimized by a proper design of the rotary joint path lengths.

.In Figure 4, the structure of the rotary joint is identical to that shown in Figure 1 with the exception'of the input and output directional devices. The directional coupler at the input in Figure 1 is replaced in Figure 4 by'a miter corner 51 extending into the waveguide 24 at an angle of 45 degrees. .The effectiveness of the mitered cornermay be increased by a folded choke (not @shown'). At the output, the directional coupler of Figure 1'is r'e placed by a hybrid T consisting of an E-plane arm 53 fed through opening 52 in the wide face 22 of circular guide 24 and H-plane arm 58 fed through opening 56 in the narrow wall 23 of the circular waveguide 24. The hybrid T is a four-arm device consisting of two colinear arms, which in this instance is provided by the waveguide 24, and the E-plane and H-

plane side arms

53 and 58 respectively. v

The hybrid T, a well known device in the waveguide art, has the special property when power is applied at one terminal of transmitting with certain prescribed amplitude and phase relationships to a second and third terminal but not to the fourth. Thus, in Figure 5, as R.-F. power is applied to the input arm 33, it propagates along path 60 of the input arm and is directed into waveguide 24 by the miter corner 51. This energy travels path '61'around the circular guide until it reaches the

openings

52 and 56 into the E and H-arms of the hybrid T. The power splits at this point and divides equally be seen that the

plugs

38 and 41 are important in increasing thepower transmission characteristics of the rotary joint since without the use of such material, breakdown across the slot gaps would occur at a lower power rating. The output of directional coupler 42 is fed to an antenna by means of a waveguide (not shown) connected to opening 43.

A directional coupler may be defined as a device which, when inserted in a transmission line with waves traveling in both directions, delivers to a pair of terminals located in an auxiliary transmission line a voltage which is largely a function of the amplitude of the wave going in one preferred direction, and relatively independent of the wave going in the opposite direction. In Figure 2, the path of the wave delivered by input guide 33 to directional coupler 35 is indicated by path 44. The.

between the arms, the power following path 62 into the E-arm while the path of the wave into the H-arm is not shown in Figure 5. In order that the hybrid T may be most useful, the inputarms should have no reflections when non-reflecting terminations are placed on the asymmetrical arms. Therefore, matching elements can be provided in the E-plane and the H-plane' arms to produce reflections that cancel the reflections from the junction. These matching elements are provided by iris 54 in E-arm 53 and iris 57 in H-arm 58 as shown in Figure 4. The arms of the T-junction will then be reflectionless when the colinear arms are terminated with reflectionless loads.

From the above description of the hybrid T, it is apparent that the wave amplitude in

arms

53 and 58 is half the amplitude of the original wave and it is further known from the waveguide art that the waves have certain phase relation with each other. The phase relation between the waves'in a hybrid varies depending upon the structure of the hybrid, but for the hybrid T the waves in the asymmetrical arms are degrees out-of-phase when .excit'ed by one of the colinear arms. Y By. taking ads/an.

gem-tea tage'is of the law ofrecipr-ocity governing hybrid Ts, the waves in theE -and H-arms may be recombined in a second hybrid T (Figure 11) to deliver the total power of the original wave to the antenna. The phase and amplituderelationot the rotary joint output arms are preservedwandthe E-arrn 53v is connected to the E-arm 1 0 of' the second hybrid T and the H-arrn 58 to the H-ai'm ltll. It is'evident that since in the second bybrid T all particulars of the energy flow in the first hybrid T are reversed, all of the power must flow out of the colinear arm 102 corresponding to the original input arm. Thus,-by the use of another hybrid T the power contained in

arms

53 and 58 of the hybrid T can be recombined and'the power of the original wave transmitted to the antenna.

The'use of the hybrid T-j-unction in the output of the rotary joint issubject to the same objection at the crossover position as when directional couplers. are used. The cross over position of the rotary joint using the hybrid T is shown in Figure 6 Wave 60 is applied through the 'input'guide 33 and upon reaching the opening 50 into waveguide 24 divides into .three paths with one component 64 being directed by miter corner 51 upward intO'H-armSS, another component 6-3 into Eearm .53 and the thirdicoruponent around the circular guide 24 along path61 The wave traveling path 61 on completing its path-around the 'circum ferenceof the rotary joint splits in'to'the two components 65 and 66. Component 65 is directed upward through opening 56 into H-arm 58 and combines with component 64 to take path 67 out of the opening 54. Component 66 is directed through opening 52 to combine with component 63, which then propa gates along path 62 in E arms S3 and out of the open+ ing' 55. On the recombination of the wave components in each respective arm, the wave components must travel "path-lengths of a wave length or multiples of a wave length to avoid arriving in an out-ofphase relation with the consequent reflection of energy'back toward the input." Although it is more difiicult in actual practice to provide path lengths of multiples of wave lengths when the hybrid T is used as the directive device, it is possible to design a rotary joint using hybrid Tswith a minimum amount of out-of-phase recombination due to the wave path lengths. v

Referring now to Figures' 7 and 8, the basic rotary waveguide' joint-of Figure 1 is converted into a switching structure by the addition of another directional coupler 70 into the wide face 22 of: circular guide 24. D1- rectional coupler 70 is identical in all respects to

directional couplers

35 and 42 and utilizes two mutually

perpendicular coupling slots

71 and 72. A high dielectric-strength plug 73 is inserted in the coupler wall opening' formed by the

slots

71 and 72. Since the output directional couplers are located on diametrically opposite sides bf'the rotary joint, itcan be seen that each coupler willwt-ransferpower during each half revolution of the rotary joint. Thus, with the input waveguide 33 located in the-position shown in Figure 8, the input wave propagatesalong path 44 and is .directionally coupled by coupler '35 into the circular waveguide 24 and along path 45. As the wave reaches the

coupling slots

39 and 40 in output directional coupler 42, the wave is directionally coupled along path 46. The directional coupler 42 thuscouples the input wave to its antenna until the input coupler has moved relative to the output coupler 42 and is directly opposite. After'the cross-over point; has been reached, the wave propagating along path 45 will be coupled into directional coupler 70 by the

slots

72 and 73 and directional coupler 42 will receive no power until immediately after the cross-over point of directional coupler 70 has been reached. Due to the properties of the directional coupler, it can be seen that other couplers can be added to waveguide 24 to provide additional "outputs to antenna feeds. Insofar as the directional coupler tails to couple 100 percent of the incident wave,': some: powefwill propagate; to. the :hominallylfoff arm: wThis extraneous-couplingican be eliminated. with a metallic plug 84 as will be discussedinthe description ofthe hybrid T joint of Figure 10. It is also evident thatthe mitered corner 51 of the plug 84 may be used to provide wave :directivity and eliminate directional coupler 35 of Figure 7.

In Figures 9 and 10, the structure of- Figure 4 is modilied to provide a switching structure utilizing two hybrid Ts. In like manner to the directional couplers of Fig.- ure 7, the hybrid Ts are located diametrically opposite from each other on the circular waveguide 24 with arm representing the H-arm and arm 81 of the E-arm of the second output hybrid'T- The path direction control of the rotary joint used as a switching structure differs somewhat from the structure used with :a single output! The cross-section view of Figure 10 illustrates the internal construction of the switching structure and shows in addition to the miter corner .51 a solid plug 84 backing up the miter corner and extending through an arc length of 180 degrees. The back-up plug 84 terminates in a plug '85 composed of a highly attenuative *lossy materialz' Figure 10 also shows the -iris8'3 located in E-arm 81 to cancel any reflections from the junction. Plug 84 may be omitted ifi minor coupling to the nonener-gized-arm can be allowed,- however, miteredcorner 51 will still be required to :.d'irect the wave along path 86.

With the input arm 33 located as shown in Figure '10, the wave path 60 propagating through the input guide 33 isdirected by the miter corner and back-up plugalon'g V the path -86-until it reaches the opening 82. into E-arm 81 Since the characteristic of hybrid Ts is that a wave propagated into one colinear' arm does not enter the other colinear arm but divides between-the side arms, the wave following path 86 will be directed-along path 87 into E-iarm 81 and upward into arm 80 not shown in this view. Should any waves propagate past the openings into the E .and H-arms of the hybrid T, .the lossy plug will absorb such energy and avoid reflections. When input arm 33 has rotated until the miter corner 51 has reached the cross-over point of thehybr-id T containingE-arm 53, the input into opposite output hybrid T will beclosed from the input wave by means of the plug '84. Thus, the input wave will be transmitted to the E and H-arms, 53 and '58 respectively, until input farm 3-3 has rotated relatively a sufiicient amount to uncover the second output hybrid T and close the first output hybrid T to the input waves. Should it be desired to add additional outputs, the arc length of the-back-up plug will be increased until only the arc length path between outputs remains uncovered. Thus, if three output hybrids are used, the

back-up plug '84 would extend .an arc length of 240 .de-'

grees and if four output hybrids were used, the back-up .plug 84 would extend for 270- degrees around the-circumferenceof the circle, 1 i Although this invention relates-to-a rotary joint suitable for 3 60degrees rotation with the necessary wave path directivity, there are many instances in which movement through only a segment of a circle is required. It is evident that the rotary joint described above can be modified to provide wave path directivity for those applications requiring relative movement between the input and output guides through any numberof degrees less than 360 degrees since it is also suitable :forcomplete rotation.

.Although the present invention has been-described with reference tospecific embodiments for botharotary joint and a switching structure, nevertheless, various modifica tions obvious to one skilled in the art that would satisfactorilyserve the teachings :of this invention 'are within the spirit, scope, and Icontemplationofthe present in vention.

'What-is claimed is:

1. A rotary :wave'guideljoiritof the type wherein high freqfuencyienergy isccdpled from .atileast'oneinput waves l7 I guide to at least one other relatively rotatable output waveguide, said joint comprising a first annular wall member, a second'annul ar wall member which is rotatable withrespect to the first annular wall member andiwhich is placedcoaxially. with and in close concentric proximity to saidfirst annular wall member to form a substantially enclosed annular waveguide cavity, means adapted to direct energy from said input waveguide into said annular waveguide, at least one opening in said annular waveguide, and means adapted to direct energy from said annular waveguide into said output waveguide, said directing means being characterized by a structural arrangement lying wholly outside said annular Waveguide and communicating with said at least one opening.

2. A rotary Waveguide joint of the type wherein high frequency energy is coupled from at least one input Wave guide to at least one other relatively rotatable output waveguide, said joint comprising a first annular wall member, a second annular wall member which is rotatable with respect to the first annular wall member and which is placed coaxially with and in close concentric proximity to said first annular wall member to form a substantially enclosed annular waveguide cavity, a directional coupler arranged to receive high frequency energy from said input waveguide andhaving' a wall in-common with said am nular waveguide' and two mutually perpendicularslots formed in said common wall with each slot resonant at the intended operating frequency of the joint whereby substantially complete transfer of energy can be effected from said coupler into said annular waveguide, and means adapted to direct energy from said annular waveguide into said output waveguide. 5 32: A joint as defined'in claim 2 wherein saidmeans adapted to direct-energy from said annular Waveguide includes a directional coupler adapted to pass energy into said output waveguide and having a wall in common with said annular waveguide and two mutually perpendicular slots formed in said common wall with each resonant at the intended operating frequency of the joint whereby substantially' complete transfer of energy can be effected from said annular waveguide into said coupler.

4. A joint as defined in claim 3 wherein a high di- 7 electric strength plug is fitted intovsaid mutually perpendicular slots.

5. A joint as defined in claim 2. wherein a high dielectric strength plug is fitted into said mutually. perpendicular slots.

6. A rotary waveguide joint of the type wherein high frequency energy is coupled from at least one input waveguide to at least one other relatively'rot'atable output waveguide, said joint comprising a first annular wall member,a second annular wall member which is rotatable with respect to the first annular wall member and which is placed coaxially with and in close concentric proximity to said first annular wall member to form a substantially enclosed annular waveguide cavity, a miter corner associated with said input waveguide and extending into said annularwaveguide adapted to direct energy from said input waveguide into said annular waveguide, openings in said wall members, and a hybrid T formed with said annular waveguideand externally thereof, said hybrid T being in communication with said openings and directing energy from said annular waveguide into said at least one output waveguide.

7. A joint as defined in claim 6 wherein said hybrid T is constitutedby said annular waveguide functioning as-two colinear arms, an E-plane side arm, and H-plane side arm, said sidearms being fed through openings in said wall members. i

-8. A joint as definedin claim 7 wherein a matching element is:located in each of said side arms to produce reflections to cancel reflections from the T-junction.

9. A joint as defined in claim 6 wherein said hybrid connected to a 'second hybrid T with correspgnding arms being connected together and said second hybridT is'adapted' to direct energy received from said first-men tioned hybrid T into said output. waveguide.

10. A rotary waveguide switching structure wherein high frequency energy is coupled from at least one input waveguide to at least two other relatively rotatable output Waveguides comprising a first annular wall member, a second annular wall member which is rotatable with respect to the first annular wall member and which is placed coaxially with and in close concentric proximity to said first wall member to form a substantially enclosed annular Waveguide cavity, means adapted to direct energy from said input waveguide into said annular waveguide, openings in said annular waveguide, and means adapted to direct energy from said annular waveguide alternately into said output Waveguides, said directing means being characterized by structural arrangements lying wholly outside said annular waveguide and communicating withsaid openings.

11. A rotary waveguide switching structure wherein high frequency energy isv coupled from at least one input waveguide to at least two other relatively rotatable output waveguides comprising a first annular wall member, a second annular wall member which is rotatable with respect to the first annular wall member and which is placed coaxially with and in close concentric proximity to said first wall member to form a substantially enclosed annular waveguide cavity, means adapted to direct energy from said input waveguide into said annular waveguide, and a directional coupler associated with each said out: put waveguide and having a wall in common with said annular waveguide and two mutually perpendicular slots formedin said common wall with each slot resonant at the design operating frequency of the structure whereby substantially complete transfer of energy can be effected from said annular waveguide into each said output waveguide, said directional couplers being symmetrically are ranged about said annular waveguide. 7 a 12. A rotary waveguide switching structure wherein high frequency energy is coupled from at least one input Waveguide to at least two other relatively rotatable output waveguides comprising a first annular wall member, a second annular wall member which is rotatable with respect to the first annular wall member and which is placed coaxially with and in close concentric proximity to said first Wall member to forma substantially enclosed annular waveguide cavity,-means adapted to direct energy from said input waveguide into said annular waveguide, openings in said annular waveguide, and at least two hybrid Ts formed with said annular waveguide and externally thereof 'in communication with said openings, said hybrid Ts being symmetrically disposed about said annular waveguide and each adapted to transfer energy from said annular waveguide into its associated output Waveguide. e l3. A'structureas defined in claim 11 wherein a high dielectric strength plug is fitted into each set of mutually perpendicular slots. 914. A rotary waveguide switchingv structure wherein high frequency energy is coupled from at least one input waveguide to at least two otherrelatively rotatable output waveguides comprising a first annular wall member, a second annular Wall member which is rotatable with respect to the first annular wall member and which is placed coaxially with and in close concentric proximity to said first wall member to form a substantially enclosed annular waveguide cavity, means adapted to direct energy from said input waveguide into said annular waveguide, energy path controlling means including a plug blocking said annular waveguide through an arc length in degrees equal to r where n is the number-of output waveguides, openings m'sa-idannular waveguide, and means symmetricailyarranged around said annular waveguide with eachin communication with at least one of said openings and associated with one of said output waveguides, each said means being adapted to direct energy into its associated waveguide from said annular waveguide.

15. A structure as defined in claim 14 wherein said plug terminates with a portion composed of a highly attenuative lossy material.

16. An antenna coupling system wherein high frequency energy is coupled from at least one waveguide to at least one other relatively rotatable waveguide which is to be connected to a rotatable antenna comprising the combination of a first annular wall member, a second annular wall member which is rotatable with respect to said first annular wall member and which is placed coaxially with and in close concentric proximity to said first wall member to form a substantially enclosed annular waveguide cavity, a directional coupler arranged to receive high frequency energy from said input waveguide and having a wall in common with said annular waveguide and two mutually perpendicular slots formed in said common wall with each slot resonant at the intended operating frequency of the joint whereby substantially complete transfer of energy can be elfected from said coupler into said annular waveguide, means adapted to direct energy from said annular waveguide into said output waveguide, a rotatable antenna, means connecting said rotatable waveguide to said antenna, and means for continuously rotating said antenna, rotatable waveguide, and rotatable wall member together as a unit.

17. An antenna coupling system wherein high frequency energy is coupled from at least one waveguide to at least one other relatively rotatable waveguide which is to be connected to a rotatable antenna comprising the combination of a first annular wall member, a second annular wall member which is rotatable with respEct to said first annular wall member and which is placed coaxially with and in close concentric proximity to said first wall member to form a substantially enclosed annular Waveguide cavity, a miter corner associated with said input Waveguide and extending into said annular waveguide adapted to direct energy from said input waveguide into said annular waveguide, a hybrid T adapted to direct energy from said annular waveguide into said output waveguide, a rotatable antenna, means connecting said rotatable waveguide to said antenna, and means for continuously rotating said antenna, rotatable waveguide, and rotatable wall member together as a unit.

References Cited in the file of this patent