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Publication numberUS3914715 A
Publication typeGrant
Publication dateOct 21, 1975
Filing dateJun 26, 1974
Priority dateJun 26, 1974
Publication numberUS 3914715 A, US 3914715A, US-A-3914715, US3914715 A, US3914715A
InventorsHubing James H, Mongold Gerald H
Original AssigneeTexas Instruments Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Coaxial ring rotary joint
US 3914715 A
Abstract
A tuned split coaxial ring rotary joint for a single channel or multichannel RF transmission line is disclosed. The tuned split coaxial ring means has a stator half in operable association with a rotatable rotor half. Multiple channels are formed by securing two rotor sections together within two stator sections. By stacking this arrangement any even number of channels can be accommodated and a single arrangement can be added for an odd number of channels.
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Description  (OCR text may contain errors)

United States Patent [19 1 Hubing et al.

[4 Oct. 21, 1975 COAXIAL RING ROTARY JOINT Inventors: James H. Hubing; Gerald H.

Mongold, both of Richardson, Tex.

Assignee: Texas Instruments Incorporated,

Dallas, Tex.

Filed: June 26, 1974 Appl. No.1 483,166

U.S. Cl 333/24 R; 333/9; 333/84; 333/97 R; 333/98 TN Field of Search 333/24 R, 84 M, 24 C, 27, 333/84 R, 97 R, 97 S, 98 R, 98 TN, 6, 9; 343/741, 743, 757, 763, 764, 766, 869

[56] References Cited UNITED STATES PATENTS 2,602,118 7/1952 Adams et al 333/24 C 2,614,171 10/1952 Fein 333/24 R X Int. C13..." H01P l/06; 1101? 3/08; H01? 5/12 2,667,578 l/l954 Barnett et al. 333/97 X 2,753,531 7/1956 Butler 333/97 2,994,046 7/1961 Granqvist 333/24 R Primary Examiner-James W. Lawrence Assistant Examiner-Marvin Nussbaum Attorney, Agent, or Firm-Harold Levine; Rene Grossman; Alva H. Bandy [5 7 1 ABSTRACT 20 Claims, 11 Drawing Figures US. Patent Oct. 21, 1975 Sheet 1 of 7 3,914,715

RFENERGY INPUT 7 Flg'l FEED -25? NETWORK SPLIT COAXIAL RING WITH TUNING SUMMING NETWORK RF ENERGY OUTPUT US. Patent Oct. 21, 1975 Sheet 2 of7 3,914,715

US. Patent Oct. 21, 1975 Sheet4 0f7 3,914,715

- U. S. Patent Oct. 21, 1975 Sheet 5 of7 3,914,715

, mm En 5 N ND mm mNN 2975 Sheet 6 of 7 3,914,715

U.S. Patent Oct. 21,

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U.S. Patent Oct. 21, 1975 Sheet7of7 3,914,715

COAXlAL RING ROTARY JOINT This invention relates to radio frequency transmission lines, and more particularly to a rotary joint for feeding either a single or multiple channel rotating device such as an antenna.

A significant component of each radio frequency transmission line for a rotating multi-beam antenna is the rotary joint. The rotary joint is a device that is designed to provide radio frequency continuity to a continously rotating antenna system. The basic rotary joint is a coaxial-line configuration operation in the transverse electromagnetic (TEM) mode. To allow rotation, the transmission line is physically broken, and halfwavelength choke sections are employed to maintain RF continuity and prevent RF leakage. Morris Cohen in A Six-Channel Vertically Stacked Coaxial Rotary Joint for the S-L and X-Band Region, Microwave Journal, Vol. 7, No. ll, November 1964, page 71, describes a rotary joint having a feed system in which energy is coupled to and from a coaxial line structure by voltage probes backed up by an effective length of shorted radial line. An impedance matching post is placed in the same plane as the voltage probe and directly opposite it. The dual rotary joint of coaxial configuration has the center conductor of the structure common to both rotary joints and is made hollow to allow passage of the cable going to the stator section of the upper rotary joint. Several rotary joints can be vertically stacked in this manner since each has a hollow center conductor. Nevertheless, the number of stacked joints is restricted by the allowable diameter of the center conductor and by the number and diameter of the stator cables which must pass through it.

To maintain a nominal characteristic impedance of from 40-60 ohms, the ratio of diameters of the inner and outer conductors of a coaxial cable for each structure must be in the order of 1.95 (for 40 ohms) to 2.72 (for 60 ohms). Therefore in the S through X band regions the mean diameters of the respective coaxial lines could permit the introduction of high order circumferential modes which effect the transmission characteristics of the rotary joints. The possibility of higher order circumferential mode interference together with the requirement for broad band frequency coverage requires a feed system capable of maintaining a constant transmission characteristic with rotation (power variation with joint rotation or WOW).

The choice of feed network depends on the composite system requirements in terms of allowable insertion loss, VSWR, frequency band of operation, bandwidth, the geometry and gain of the antenna, and the available space in its use environment such as, for example, an aircraft, or spacecraft. At frequencies above 3 gigahertz (Gl-lz), half wavelength chokes provide a compact broadband and reliable means of insuring electrical continuity in the rotary joint, however, at lower frequencies the choke widths and lengths become prohibitive and lead to very bulky components. The halfwavelength choke section at one GHz, for example, is approximately 30 centimeters long. A multi-channel rotary joint at this frequency using chokes becomes expensive to manufacture, difficult to handle, and prohibitive in size.

An alternative solution to the need for electrical continuity has been the use of precious metal contacts at the cut surfaces of the inner and outer conductors of the coaxial cable. Advantages obtained by using a precious metal contact are that it reduces the space requirement and has very broad bandwidth characteristics; it disadvantage lies in the fact that the silver graphite material constituting the contact rubs on a hardened surface such as coin silver and wears out. As the graphite wears it creates loose graphite and silver particles that can damage bearings and contaminate the RF transmission line. Because of the materials involved, the assembly problems, and the limited life time, the precious metal contact turns out to be a very expensive item, particularly in multi-channel rotary joints.

As object of the present invention is to provide a durable compact rotary joint for use in RF transmission lines at frequencies, for example, below three gigahertz.

Another object of the present invention is to provide a radio frequency rotary joint which, at frequencies below three gigahertz, is more economical to manufacture than other known rotary joints designed to operate at these frequencies.

Still another object of the present invention is to provide a multichannel radio frequency rotary joint which is more reliable and which enjoys a longer operating life than a precious metal contact type rotary joint.

Yet another object of the invention is to provide a rotary joint for a radio frequency energy transmission line which operates with a VSWR of about 2 or less.

Still yet another object of the invention is to provide a rotary joint for a radio frequency energy transmission linewhich is adaptable to a plurality of configurations to provide system design flexibility.

Briefly stated, the rotary joint for radio frequencyenergy constituting the present invention comprises: either a power divider for a multiple feed system or a coaxial feed line for single lead feed system to supply radio frequency energy to a tuned split coaxial ring; and a summing network for collecting the RF energy from the split coaxial ring. The coaxial ring is a toroidally shaped ring of coaxial cable divided into two halves along the plane of the ring. One ring half forms a stator for the rotary joint; and RF energy from the multiple feed system is fed from the power divider, or for a single line feed system from the coaxial feed line, into the stator half of the split coaxial ring. Transition impedances are matched in the coaxial ring by at least one tuner which tunes the coaxial ring to a selected band of frequencies. The second half of the split coaxial ring forms a rotor supported for rotation by bearings. The ring halves are aligned and to prevent contact during rotation the ring halves are spaced or gapped. The gap is maintained small as compared to the coaxial dimensions. RF energy is collected from the rotor by a summing network which is similar to the construction of either the power divider or the coaxial feed line whichever is used. From the summing network, the power is fed to the power output connector.

The above objects and other objects and features of the invention will become more readily understood in the following detailed description taken in conjunction with the drawings in which:

FIG. 1 is a block diagram of an RF energy rotary joint utilizing the split coaxial ring rotary joint.

FIG. 2 is an isometric view of a split coaxial ring for use in the rotary joint of an RF energy transmission line.

FIG. 3 is a sectional view of a coaxial ring rotary joint using a single lead feed system.

FIG. 4 is a view of a multi-channel rotary joint arrangement depicting a two channel coaxial ring rotary joint atop a coaxial waveguide rotary joint; the housing for the rectangular waveguide partly broken away to show the coaxial waveguide rotary joint in section.

FIG. 5 is a sectional view of the two channel split coaxial ring rotary joint.

FIG. 6 is an isometric view of another multi-channel arrangement depicting a multi-channel split coaxial ring rotary joint in combination with a multi-channel coaxial waveguide rotary joint.

FIG. 7 is a cross-sectional view of the multiple feed multi-channel split coaxial ring rotary joint utilized in the rotary joint of FIG. 6.

FIG. 8 is a broken sectional view of the feed line connection of the source of RF energy to the power divider of FIG. 6.

FIG. 9 is a broken sectional view of the feed lines interconnecting the power divider and split coaxial ring of FIG. 6.

FIG. 10 is a broken sectional view of the tuner used in the split coaxial ring rotor joints of FIG. 6.

FIG. 1 l is a plan view of a conductor pattern for a six feed line power divider for FIG. 6.

Referring to FIG. 1 in which there is shown a radio frequency (RF) split coaxial ring rotary joint 10 for coupling a stationary system (not shown) to a rotating system such as a rotating radar antenna (not shown). The RF feed line system comprises an input terminal 12 for receiving RF energy for a source thereof. Feed network 14 is coupled to the RF energy input 12 and to a stationary half (stator) of a split coaxial ring rotary joint 16 through one or more feedlines. An RF energy summing network 18 is connected to a rotating half (rotor) of the split coaxial ring rotary joint 16 to collect through one or more output lines the RF energy from the continuous path provided by the split coaxial rotary joint 16. An RF energy output terminal 20 is coupled to the output of the summing network 18.

Referring now to FIG. 2 in which there is shown a basic split coaxial ring 22 for a rotary joint 16. The split coaxial ring may be constructed of any suitable conductor material such as, for example, aluminum. The length around the coaxial rings center line is onequarter wavelength or less. For split coaxial rings of one-quarter wavelength or less the feed network 14 and the summing network 18 consist of the feedlines and the output lines which are lengths of coaxial cables terminating, respectively, at the input and output connectors 12 and 20. The feed netowrk 14 or cable is connected to the upper half or stator of the split coaxial ring 22 and the summing network 18 or cable is connecteed to the lower half or rotor of the split coaxial ring. To tune the coaxial ring 22 to the desired frequency, the stator and rotor of the split coaxial ring are provided with tuners 24 and 26. Tuner 24, connected to the stator of the coaxial ring 22, is spaced 120 from the stators feed network 14 input connection, and tuner 26, connected to the rotor of the coaxial ring 22, is spaced 120 from the rotors summing metwork 18 output connection. The upper and lower halves of the inner conductor (not shown) of the coaxial ring 22 are supported on an axis common to the inner and outer conductors, each by three equally spaced nonconductive pins 28 having ends mounted in the outer conductor halves of the split coaxial ring 22.

A rotary joint embodying the coaxial ring 22 of FIG. 2 is demonstrated in FIG. 3. The stator 30 is an inverted cylindrical cup shaped member. The stators half of the coaxial rings outer conductor 32 is formed in the inner surface of the bottom of the cup and the stators half of the inner conductor 34 is centrally disposed about an axis common to the inner and outer conductor halves and supported there by the nonconducting pins 28. The flat surface 36 of the inner conductor is substantially coplanar with the inner surface of the stator 30. RF energy is fed from a source thereof (not shown) to the stator 30 through a feed network 14 consisting of a single coaxial cable. The inner conductor 38 of the feed networks coaxial feed cable terminates in the stators inner conductor half 34 of the coaxial ring; the outer conductor 40 of the feed networks coaxial cable terminates at the stators half of the outer conductor 32 of the coaxial ring. The tuner 24 of the stator 30, which may be, for example, a shorted section of the coaxial cable, is coupled to the stators half of the split coaxial ring 120 from the feed line connection. The tuner is coupled to the stators half of the coaxial ring as was the coaxial feed line and fine tunes the frequency of the stator.

The rotor 42 of the split coaxial ring rotary joint is also an inverted cylindrically cup shaped member rotatably mounted within the walls and spaced about 0.004 inch from the bottom of the inverted cylindrically cup shaped member of the stator by bearings 44. The rotors half of the outer conductor 46 of the split coaxial ring is formed in the outer surface of the bottom 48 of the rotor and the rotors half of the split coaxial rings inner conductor 50 is supported about an axis common to the inner and outer conductors by three nonconductive pins 28 having ends mounted in the outer conductor. The summing network 18 cable has the output connector 20 at one end, and its other end connected to the rotors half of the split coaxial ring in a manner identical to that of stators power divider feed network cable. A tuner 26, which may be identical in construction to tuner 24 of the stator, is connected to the rotors half of the split coaxial ring 120 from the summing networks connection thereto.

FIG. 4 shows a multichannel rotary joint consisting of a combination of two split coaxial ring rotaty joints and a coaxial waveguide rotary joint; The split coaxial ring rotary joints are for frequencies below 3 GI-Iz, and the coaxial Waveguide rotary joint is for frequencies above 3 GI-Iz. It will be understood that the choice of the two configurations is determined by matters of economics. The coaxial waveguide rotary joint is cheaper to fabricate at frequencies above 3 GI-Iz than is the split coaxial ring rotary joint. At frequencies below 3 GHz the choke structure of the coaxial waveguide becomes too large and heavy for easy handling and aircraft or spacecraft use; therefore, the coaxial ring is preferred. As the split coaxial ring rotary joint structure and the coaxial waveguide rotary joint are compatible, as will become more apparent as the description proceeds, they make an ideal combination for a multichannel rotary joint.

A combined multichannel rotary joint is shown in FIG. 4 in which two coaxial cables 60 and 62 are provided with connectors 68 and 70 for coupling to sources of RF energy at frequencies, for example,

below 3 Gl-Iz. A rectangular waveguide 66 is provided with a rectangular flange 72 for coupling to a source of RF energy at frequencies, for example, above 3Gl-Iz.

The coaxial cable feed lines and 62 are attached to two split coaxial ring rotary joints enclosed by housing 74. The housing 74 is mounted atop housing for a coaxial waveguide rotary joint; A drive tube 82 is connected to the rotors of the split coaxial ring rotary joints and has one end forming keyways for splines joining a tubular member 84. Member 84 is mounted on bearings 86 which are retained in a bearing insert 88. The bearing insert 88 is attached by screws 90 to stator 92 of the coaxial waveguide rotary joint. The tubular member 84 consistutes the inner conductor of the coaxial cable for the coaxial waveguide rotary joint. Stator 92 is shaped to form with the bearing insert 88, a choke 94 for the inner conductor 84. The rectangular waveguide 66 opens into the coaxial cable 96 below the choke 94, and the choke acts to maintain electrical continuity between the stator 92 and the inner conductor 84 and to reduce loss of power. The RF energy in the rectangular waveguide 66 is conducted in the dominate mode (TE and is converted to the dominant (TEM) mode in the coaxial cable by a crossed waveguide transition including a transformer 98 and a tuner 99 formed in the housing 80 opposite the opening for the rectangular waveguide 66.

The stator 92 extends downwardly and inwardly from the housing rectangular waveguide opening to form the outer conductor 100 of the coaxial cable 96. The bottom flange 102 of the bottom flanged tubular member 84 supports a rotor 103 which includes a transformer 104 adjacent to the rotor output 106 of the output section of the rectangular waveguide 66 and an outer conductor choke 110. The transformer 104 converts the RF energy from the TEM mode back to the TE mode for the output section of the rectangular waveguide 66. The rotor 103 is rotatably mounted in the lower end of stator 92 on bearings 108. The outer conductor choke 110 prevents loss of RF energy through the pair of bearings 108, which are retained between the rotor and stator by hearing nut 1 1 1. The choke 1 10, bearings 108 and bearing retaining nut 111 are in sealing engagement with a seal 112.

Turning now to the multichannel split coaxial ring rotary joint 16 (FIG. 5), the rotor 103 (FIG. 4) of the coaxial waveguide rotary joint is connected to the rotors 114 and 116 (FIG. 5) of the two channel split coaxial ring rotary joint 16 by the tubular member 84 splined to the drive tube 82 (FIG. 4). The rotors 114 and 116 (FIG. 5) are attached to the drive tube 82 for rotation. Rotor 114 is a cylindrically shaped block 118 of conductive material such as, for example, aluminum having a centrally disposed aperture with walls engaging the tubular drive 82 for rotation. The lower surface of block 118 is shaped to form the upperhalf 120 of the outer conductor of a split coaxial ring 122. The upper half of an inner conductor 124 for the split coaxial ring is supported concentrically within the upper half 120 of the outer conductor by three nonconductive pins 126 spaced 120' one from another.

As this particular multichannel rotary joint arrangement permits the coaxial rings to be AA or less in length, and as a single feedline provides adequate performance neither a power divider nor a summer is required. Thus, rotor 114 requires only one summing or output feedline. Summing line 128 is a coaxial line having its inner conductor connected to the inner conductor of the split coaxial ring 122 and its outer conductor connected to the outer conductor of the split coaxial ring 122. The summing line 128 is fed through the tubular drive member 82 and bottom flanged tubular member 84 to its output terminal. A tuner 130, which may be a short piece of coaxial cable having one end selectively short circuited is attached to the rotor as part of the tuning system in the split coaxial ring. The tuner is located, when looking at the split side of the ring, 120 measured clockwise from the summing line connection to the split coaxial ring.

The rotor 116 for the second channel has the lower half or output half of the split coaxial ring 132 formed in the outer surface 134 of the cross member of a cylindrically cup shaped member 136. As the construction of the rotor half of the split coaxial ring 132 is substantially identical to that of the rotor for the split coaxial ring 122, it is not described. The difference is that its summing line 138 connection is spaced from the summing line 128 connection of rotor 114, and the tuner 140 when observed from the split side, is 120 measured counterclockwise from the summing line 138. The cylindrical sides of rotors 114 and 116, respectively, have recesses in which bearings 142 and 144 are mounted; shims 146 may be used to adjust the bearings within the recesses. A screw 152 locks together the rotors 114 and 116 to load bearings 142 and 144 to gap the rotors 114 and 116 from stators 148 and 150.

The stator 148 comprises an inverted cylindrically cup shaped member 154 having: at its lower end an outwardly extending flange member 156, adapted to receive the housing 74 and to rest upon the housing 80 of the choke type rotary joint (FIG. 4); and at its upper end a recess 158 with an O-ring 160 (FIG. 5). The recess and O-ring receive and seal a narrow flanged end 162 of stator 150. The bottom or cross-member 164 of the cup shaped member 154 has a centrally disposed aperture 166 through which the drive tube 82 extends. The outer conductor 168 forming the lower half of the split coaxial ring 122 is formed in the upper surface of the cross-member 164. The inner conductor 172 of the split coaxial ring is concentrically mounted in the outer conductor by nonconductive pins 174 spaced 120 one from another. As no power divider is required for this arrangement, the coaxial feedline 60 has its inner conductor attached to the inner conductor 172 of the lower half of the split coaxial ring, and its outer conductor 176 attached to the outer conductor 168 of the split coaxial ring for transferring the RF energy from the feedline 60 to the lower half of the split coaxial ring 122 in the primary TEM mode. A tuner 178 identical in construction to tuner 130 is attached to the lower half of the split coaxial ring 122 to complete the tuning in the split coaxial ring. The cup cavity 179 is filled with a suitable potting compound such as, for example, a silicon rubber sold under the trade mark 3144 RTV by Dow Corning Corporation to support the tuner 178 and feedline 60.

The stator 150 comprises a cylindrically cup shaped member having a flange 180 extending upwardly from the cross-member 182 and a cylindrical side terminating in a downwardly extending narrow flange 162. As the upper half of the split coaxial ring 132 is identical in construction to that of the above described lower half formed in stator 148, it will not be described. It is to be observed that as no power divider is required for this arrangment, the coaxial feedline 62 is attached directly to the upper half of the split coaxial ring 132 and the tuner 184 is spaced 120 from the feedline 62. The cup cavity 186 between flange 180 is potted with a potting compound such as, for example, an epoxy sealer sold under the trademark Devcon F-2 by Devcon Corporation to support the tuner 184 and feedline 62.

Referring now to FIG. 6 in which there is shown another combination arrangement for a multichannel rotary joint 190. In this arrangment three high frequency channels such as, for example, 5 band channels 192, 194, and 196 are combined with two low frequency channels 198 and 200 such as, for example, L" band channels. The L band channels are positioned between the S band channel inputs and outputs. The arrangment of FIG. 4, that is, where the low frequency channels are positioned at the end of the high frequency channel would be an objectional arrangment for the combination of FIG. 6 as a substantial length (about 4 feet) of coaxial cable of the L band channels would have to pass through the length of the coaxial waveguide channels. Incorporating the length of the coaxial cable for the L bands through the center of the coaxial waveguide channels would make the S band coaxial tubes substantially difficult to work with while maintaining the desired TEM mode. To reduce the number of coaxial cables the two split coaxial ring joints for the L band channels are centrally positioned in housing 201 (FIG. 6) with their output feedlines taken outside the 3 S-band channels.

The arrangment of the multichannel split coaxial rings in combination with multichannel choke type rotary joints (FIG. 6) includes at the input end azimuth position indicators (APG) 202 which may be, for example, shaft encoders as sold by Litton Industries. The APG 202 are servo type instruments driven by a rod 204 (FIG. 7) centrally disposed in drive tube 220 and connecting the drive shaft of the APG to the rotating antenna (not shown). The first S band channel 192 (FIG. 6) has'a coaxial cable connector (Type N) 208 which connects to a source (not shown) of RF energy at, for example, S band frequencies. The RF energy entering the connector is transmitted into the inner coaxial waveguide rotary joint via a right angle stub 210 surrounding the APG drive rod 204. The rotary joint may be a choke type rotary joint such as that described in conjunction with FIG. 4. The coaxial cable of the inner rotary joint has its inner conductor (FIG. 7) formed by the APG drive rod 204, and its outer conductor 212 held in spaced relationship about the inner conductor 204.

The second S band channel 194 (FIG. 6) has a rectangular waveguide flange 216 for connecting a rectangular waveguide feedline from a source of RF energy (not shown). The RF energy is fed from the flange 216 into a door knob type rotary joint 218 utilizing a door knob transition structure such as that disclosed by George L. Ragan, Microwave Transmission Circuits, p. 45 4, McGraw-Hill Book Company, Inc. 1948.

The rotary joint utilizes the outer conductor 212 of the channel 1 coaxial cable as its inner conductor and has an outer conductor 214 spaced therefrom (FIG. 7).

The third S band channel 196 (FIG. 6) has a rectangular waveguide flange 222 for connecting to a rectangular waveguide feedline from a source of RF energy (not shown). The rotary joint 224 utilizes a cross waveguide transition disclosed at p. 239 and 240 of Ragans Microwave Transmission Circuits textbook cited above. The third coaxial waveguide channel utilizes the outer conductor 214 of the second rotating coaxial cable as its inner conductor and utiliizes the drive tube 220 as its outer conductor (FIG. 7).

RF energy for channel 1 (FIG. 6) passes through the coaxial connector 208 in the TEM mode through the right angle stub 210 and is conducted by the center rotating coaxial cable formed about drive rod 204 to the coaxial cable outlet connector 226 which is, for example, a type N connector. RF energy for channel 2 enters rectangular waveguide flange 216 in the TE mode and passes through the door knob type rotary joint 218 for transition from the TE mode to the TEM mode and is conducted by the second or middle rotating coaxial cable to rectangular waveguide takeout 227 where it is reconverted to the TE mode and conducted through output flange 228. RF energy for channel 3 enters rectangular waveguide flange 222 in the TE mode and passes through a crossed waveguide transition 224 for conversion from the TE to the TEM mode for conduction by the third or outer rotating coaxial cable rectangular waveguide takeout 229 where the TEM mode is converted back to the TE mode and collected at rectangular waveguide flange 230.

The two L band channels 198 and 200 pass through the center housing 231 to housing 201 in which is mounted the dual split coaxial ring rotary joint 232 (FIG. 7 As the split coaxial ring rotary joint surrounds the three coaxial waveguide S band channels, the circumferences of the split coaxial rings 234 and 236 at L band, for example, are more than AA; thus, more than one feedline (FIG. 1) is required to feed each of the split coaxial rings. By feeding these large tuned split coaxial rings with suitable power dividers at electrical degree intervals, a voltage standing wave ratio (VSWR) of less than 1.2 and a WOW (VSWR variation with joint rotation of less than 0.05 can be maintained. The rotary joint input feed lines 198 and 200 feed RF energy to power dividers 240 and 242 (FIG. 7) (hereinafter described) through connections .244 and 246, and through a plurality of feedlines 252 (hereinafter described) to the stator halves 248 and 250 of split coaxial rings 234 and 236. The RF energy is collected from halves of the split coaxial rings 234 and 236 formed in rotors 254 and 256 through a corresponding plurality of power output leads 257, which are identical in construction to the input feedlines 252. The feedlines 257 feed the RF energy to summing networks 258 and 260. Summing networks 258 and 260 are identical in construction to power dividers 240 and 242. Connectors 262 and 264, which are identical in construction to connectors 244 and 246, connect the RF energy output to the output coaxial feedlines 266 and 268.

The stator halves 248 and 250 of the split coaxial rings 234 and 236 are formed in flanged annular rings 270 and 272. A duplex pair of bearings 280 is seated in recesses of the inner edges of the flanges and the bearings rotatably support flanged rotors 254 and 256. The flange of stator 270 is provided with a plurality of threaded passages 274 in its depending edge which mate with passages 276 in stator 272 through which screws 278 are passed to join the stators 270 and 272 together and to hold the bearings 280. The rotor halves 282 and 284 of the split coaxial rings 234 and 236 are formedin rotors 254 and 256. The rotors 254 and 256 have flanges with outer recesses adjacent the ends of the flange to support races of the bearings 280. The rotors 254 and 256 are held together by a plurality of screws 288. The arrangment of the bearings 280 and the stator and rotor screws 278 and 288 maintain a gap between the rotor and stator halves of the split coaxial rings 234 and'236 at about, for example, 0.005 inch.

The split coaxial rings 234 and 236 each have split inner conductors 290-291, which may be, for example, an aluminum ring split in half along the plane of the ring, and two tuners 289 (FIG. 10) positioned 180 apart and midway between adjacent feedpoints in either the rotors or stators. The halves of the inner conductor (FIG. 7) are concentrically positioned within the outer conductors 292-293 so that their'axes are common to those of the outer conductors and each half is supported therein by the feedlines 252. As the tuners 289 (FIG. 10) are identical only one is described. Each tuner 289 is, for example, a metal rod or tube mounted in the split coaxial ring to do. short the inner and outer conductors 291 and 292 of the coaxial rings.

The split coaxial rings 234 and 236, as previously mentioned, have a plurality of input feedlines and collector lines 252 (FIGS. 1, 7 and 9) spaced 6O electrical degrees one from the other. As each input feedline and collector line is identical in construction only one is described. Each input feedline or output feedline (FIG. 9) includes an insulated feed pin 294 having one end 295 connected to a half of the split inner conductor 291, its insulated body passing from the inner conductor 291 through stator 270 or 272 or a rotor 282 or 284 as the case may be to a takeoff 296 of the power divider 240 for the feedline or the summer for the collector output line. The power dividers 240 and 242 (FIGS. 7 and 11) and summing networks 258 and 260 are identical in construction, thus, only the power divider 240 is described in detail. The'power divider, for example, is a six-way stripline power divider having a conductor pattern 298 (FIG. 11) for producing equal amplitude and equal phase outputs. The pattern is formed on the dielectric 300 (FIG. 7). A patternless printed circuit board 302 is positioned to form a dielectric over the patterned board 298; and an aluminum plate 304, which is secured to the stator 270 by screws 306, forms an upper ground plane for the power divider. The upper surface of the stator 270 forms a lower ground plane. Y

RF energy at frequencies below 3 GI-Iz is fed the power dividers 240 and 242 and taken from the summing networks 258 and 260 through right angle launch mechanisms 244, 246 and 262, 264. As each launch mechanism is identical in construction only one is described. The launch mechanism 244 (FIG. 8) comprises an energy launch member 308, a dielectric insert 310, and center contact 312. The launch member 308 has one end connected to the outer conductor of the coaxial feed cable 200, a body portion which passes through the ground plane 304, and another end forming an outwardly extending flange to secure the launch member to the ground plane 304. The dielectric insert 310 separates the launch member 308 from thecenter contact 312. The center contact 312 is theinner conductor of the coaxial feedline or an extension thereof which is in contact with the input point 314 (FIG. 11) of the conductor pattern 298.

In operation of the two split ring rotary joint channels, RF energy at, for example, L band frequencies is fed through the coaxial feedlines 200 and 198 (FIG.

' 7) to connectors 244 and 246 connecting the feed lines to the power dividers 240 and 242. The conductor pattern 298 (FIG. 11) of each power divider divides the RF energy equally amongst six feed lines 252 (FIG. 7),

which feed the RF energy to the stator halves of the split coaxial rings 234 and 236 at six different points spaced 60 electrical degrees apart. Tuners 289 (FIG. tune the VSWR and WOW of the coaxial rings 234 and 236, and this tuned RF energy is collected from the rotor halves by six collector lines 257 corresponding to the feed lines 252 (FIG. 7) The collector lines 257 couple the RF energy to the summing networks 258 and 260, which are identical in construction to the power divider 240 (FIG. 11). Coaxial type output feed lines 266 and 268 are coupled to the summing network output points for conducting the collected RF energy to output terminals.

From the summing network, the output feed lines 266 and 268 exit housing 201 (FIG. 6) adjacent the drive tube 206 and terminate at connectors 315 and 316 coupled to a support plate 318 (FIG. 6).

A slip ring arrangement for coupling electrical current to ancillary equipment is provided the rotary joint 190 through receptacle 320 (FIG. 6) mounted in housing 231. The housing 231 supports brushings 324 for a plurality of annularly shaped slip rings 326 which include conductors mounted on the faces of an insulated support ring. The slip rings 326 are mounted for rotation with the drive member 206. Leads 328 from the slip rings pass along the drive member 206 through the housing 201 and exit housing 201 in passages 329 formed in rotating member 330 of the housing 201. The slip ring leads terminate in plug 332 mounted in support member 318.

Although preferred embodiments of the present invention have been described in detail, it is to be understood that various changes, substitutions, and alterations can be made therein and more specifically any number of split coaxial rings may be joined for the rotary joint without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

l. A rotary joint for supplying RF energy through a system having a stationary member and a rotating member comprising:

a. an RF energy input feed line means coupled to a source of RF energy;

b. a rotary joint means, said rotary joint means including a split coaxial, ring-shaped cable means having a stator half electrically coupled to the stationary member through the input feed line means, and a rotor half electrically coupled to the rotating member; and

c. an RF energy output collecting means operatively coupled to the rotor half for collecting the RF energy passing through the split coaxial, ring-shaped cable means.

2. A rotary joint for an RF transmission line comprising:

a. an RF energy coaxial feed line means coupled to an RF energy source, said coaxial feed line means having an outer conductor and an inner conductor;

b. a rotary joint means including an RF energy coaxial, ring-shaped line having its outer and inner conductors split to provide a stator portion and rotor portion, said outer and inner conductors of the stator portion connected, respectively, to the outer and inner conductors of the RF energy input coaxial feed line; and

c. an RF energy coaxial, collectorline means, said coaxial, collector line means having outer and inner conductors coupled, respectively, to the outer and inner conductors of the rotor portion of the split coaxial, ringshaped line to collect the RF energy, said collector means including an output terminal for coupling the RF energy to a rotating member.

3. A rotary joint for an RF transmission line according to claim 2, wherein said RF energy coaxial feed line means includes a power divider for selectively feeding RF energy to the stator half of the split coaxial ring.

4. A rotary joint for an RF transmission line according to claim2, wherein said split RF energy coaxial, ring shaped line includes an outer conductor means formed in a stator and an outer conductor means formed in a rotor, said outer conductor means supporting, respectively, first and second inner conductor means of the split coaxial ring means.

5. A rotary joint for an RF transmission line according to claim 2, wherein said RF energy coaxial collector line means includes a summing network for collecting the RF energy output of the split RF energy coaxial, ring shaped line rotor half into a single RF energy output.

6. A rotary joint for an RF transmission line according to claim 2 wherein said RF energy coaxial, ring shaped collector line means comprises a first dielectric, a conductor pattern supported by said first dielectric, a second dielectric covering the conductor pattern, and a ground plane member covering the second dielectric, said ground plane, first and second dielectrics, and conductor pattern attached to a rotor member of the split coaxial ring, said rotor member acting as a second ground plane for the collector means, a plurality of coaxial feed lines coupled to the rotor half of the split coaxial ring for collecting RF energy for the conductor pattern of the collector means, and an RF energy output line coupled to the output terminal of the conductor pattern for providing a combined RF energy output.

7. A rotary joint for an RF transmission line according to claim 3 wherein said power divider is a strip line having a conductive pattern for dividing aninput of RF energy into a plurality of RF energy outputs to a corresponding plurality of feed lines, said plurality of feed lines coupled to the split coaxial ring for feeding RF energy at selected electrical degree intervals to the split coaxial ring.

8. A rotary joint for an RF transmission line according to claim 3 wherein said power divider comprises a first dielectric, a conductor pattern supported by said first dielectric, a second dielectric covering the conductor pattern, and a ground plane member covering the second dielectric, said ground plane member, first and second dielectrics, and conductor pattern attached to a stator member of the split coaxial ring, said stator member acting as a second ground plane for the power divider, an RF energy feed line operatively coupled to the conductor pattern for supplying the RF energy to the power divider, and a plurality of coaxial feed lines coupled to a corresponding plurality of output terminals of the conductor pattern for coupling RF energy to the stator half of the split coaxial ring.

9. A rotary joint for an RF transmission line according to claim 4 wherein said split RF energy coaxial, ring axial ring for a rotating member, and said tuner means operatively coupled to the split coaxial ring for tuning the RF energy to a desired frequency band.

10. A rotary joint for an RF transmission line according to claim 9, wherein said inner conductor halves of the split, ring shaped coaxial line are supported concentrically within the outer conductors by a plurality of nonconductive pins.

11. A rotary joint for an RF transmission line according to claim 9, wherein said inner conductive halves of the split, ring shaped coaxial line are supported by the feed lines.

12. A rotary joint for an RF transmission line according to claim 9, wherein said inner conductor of the stator half is supporte in spaced relationship to the outer conductor of the split coaxial ring, said outer conductor formed in a cylindrically cup shaped stator member, and said inner conductor of the rotor half of the split coaxial ring supported in spaced relationship to the outer conductor of a cup shaped cylindrical rotor member, said rotor member rotatably supported by the stator member with the stator and rotor halves of the split coaxial ring aligned to form the split, ring shaped coaxial line.

13. A rotary joint according to claim 12 wherein said multichannel rotary joint means comprising a plurality of split, ring shaped coaxial line rotary joints further comprises a plurality of coaxial waveguide rotary joints having spaced input and output terminals, said plurality of coaxial waveguide rotary joints having concentric inner conductors, the inner conductor of each successive coaxial cable forming the outer conductor of each preceding coaxial cable, and said inner and outer conductors coupled together to form a rotating drive member for the rotors of the plurality of split, ring shaped coaxial line rotary joints, said plurality of split, ring shaped coaxial line rotary joints mounted concentrically about the coaxial waveguide rotary joints intermediate their input and output terminals, and having their rotors attached to the rotating drive member for rotation therewith.

14. A rotary joint for an RF transmission line comprising:

a. an RF energy feed line means coupled to an RF energy source;

b. a rotary joint means including a split coaxial cable means having a ring shape and including a stator portion, a rotor portion, and a tuning system, said stator portion operatively connected to the RF energy feed line means for receiving RF energy into the split coaxial cable means having a ring shape, said tuning system having a post for tuning the RF energy in the split coaxial cable means having a ring shape to a desired frequency band, and said rotor portion coupled in rotatable association with said stator portion for coupling the RF energy to a collector means; and a collector means having output feed line means coupled to the rotor portion of the split coaxial cable means having a ring shape to collect the RF energy, said collector means including an output a. an' RF energy feed line means coupledto RF en-- ergy sources: I v t 1 b. a multichannel rotary joint means, said multichannel rota'ry joint'comprising a plurality of tuned split, ring shapedcoaxial linesforming a plurality of stator halves anda corresponding plurality of rotor halves, said plurality ofrotor halves mechani- 1 .cally connected one to another and each of said plurality of rotors electrically coupled to a collector means, and said plurality of stator halves mechanically connected one to another and each of said plurality of stators electrically coupled to the RF energy feed line means and rotatably supporting the rotor halves with the split, ring shaped coaxial line halves of the rotors and stators forming a plurality of split, ring shaped coaxial lines for a corresponding plurality of RF energy channels; and

. collector means for collecting RF energy from the rotor halves of the split, ring shaped coaxial lines of the multichannels.

16. A rotary joint for a multichannel transmission line according to claim wherein said multichannel rotary joint comprising a plurality of tuned split, ring shaped coaxial line rotary joints is mounted adjacent to a second rotary joint having one or more coaxial waveguide transfer means, said coaxial waveguide transfer means having a tubular inner conductor operatively connected to the rotors of the split, ring shaped coaxial lines for rotating the rotors and providing a passage for the rotors output feed lines of the plurality of split coaxial ring rotary joints.

17. A rotary joint for an RF transmission line comprising:

a. an RF energy feed line means coupled to an RF energy source;

b. a rotary joint means including a split coaxial ring having a stator half, and a rotor half, said stator half operatively connected to the RF energy feed line means for receiving RF energy into the split coaxial ring means, and said rotor half coupled in rotatable association with said stator half for coupling the RF energy to a collector means; and

c. a collector means having output feed line means coupled to the rotor half of the split coaxial ring to collect the RF energy, said collector means including an output terminal for coupling the RF energy to a rotating member, wherein said RF energy collector means comprises: a first dielectric, a conductor pattern supported by said first dielectric, a second dielectric covering the conductor pattern, and a ground plane member covering the second dielectric, said ground plane, first and second dielectrics, and conductor pattern attached to a rotor member of the split coaxial ring, said rotor member acting as a second ground plane for the collector means, a plurality of coaxial feed lines coupled to the rotor half of the split coaxial ring for collecting RF energy for the conductor pattern of the collector means, and an RF energy output line coupled to the output terminal of the conductor pattern for providing a combined RF energy output.

18. A rotary joint for an RF transmission line comprising:

a. an RF energy feed line means coupled to an RF energy source, wherein said RF energy feed line meansincludes a power divider for selectively feeding. RF energy to the stator half of the split coaxial ring, wherein said power divider is a strip line having a conductive pattern for dividing an input of RF energy .into a plurality of RF energy outputs to I a=corresponding plurality of feed lines, said plurality of feed lines coupled to the split coaxial ring for tervals to the'split coaxial ring; b. a rotary. joint means including a split coaxial ring having ,a stator half; and a rotor half, said stator half operatively connected to the RF energy feed line means for receiving RF energy into the split coaxial ring means, and said rotor half coupled in rotatable association with said stator half for coupling the RF energy to a collector means; and a collector means having output feed line means coupled to the rotor half of the split coaxial ring to collect the RF energy, said collector means including an output terminal for coupling the RF energy to a rotating member. 1

19. A rotary joint for an RF transmission line comprising:

a. an RF energy feed line means coupled to an RF energy source wherein said RF energy feed line means includes a power divider for selectively feeding RF energy to the stator half of the split coaxial ring, wherein said power divider comprises a first dielectric, a conductor pattern supported by said first dielectric, a second dielectric covering the conductor pattern, and a ground plane member covering the second dielectric, said ground plane member, first and second dielectrics, and conductor pattern attached to a stator member of the split coaxial ring, said stator member acting as a second ground plane for the power divider, an RF energy feed line operatively coupled to the conductor pattern for supplying the RF energy to the power divider, and a plurality of coaxial feed lines coupled to a corresponding plurality of output terminals of the conductor pattern for coupling RF energy to the stator half of the split coaxial ring;

b. a rotary joint means including a split coaxial ring having a stator half, and a rotor half, said stator half operatively connected to the RF energy feed line means for receiving RF energy into the split coaxial ring means, and said rotor half coupled in rotatable association with said stator half for coupling the RF energy to a collector means; and

c. a collector means having output feed line means coupled to the rotor half of the split coaxial ring to collect the RF energy, said collector means including an output terminal for coupling the RF energy to a rotating member.

20. A rotary joint for an RF transmission line com-' prising:

a. an RF energy feed line means coupled to an RF energy source,

b. a rotary joint means including a split coaxial ring wherein said split coaxial ring includes an outer conductor means formed in a stator and an outer conductor means formed in a rotor, said outer conductor means supporting, respectively, first and second inner conductor means of the split coaxial ring means, wherein said split coaxial ring comfeeding RF energy at selected electrical degree in- I prises an outer conductor ring, and an inner conductor ring, said outer and inner conductor rings having a common axis and split in half along the plane of the ring to form a stator half for receiving RF energy from a stationary member, and a rotor half for transferring RF energy from the split coaxial ring for a rotating member, and said tuner means operatively coupled to the split coaxial ring for tuning the RF energy to a desired frequency band, wherein said inner conductor of the stator half is supported in spaced relationship to the outer conductor of the split coaxial ring, said outer conductor formed in a cylindrically cup shaped stator a collector means having output feed line means coupled to the rotor half of the split coaxial ring to collect the RF energy, said collector means including anoutput terminal for coupling the RF energy to a rotating member.

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Referenced by
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Classifications
U.S. Classification333/24.00R, 333/125, 333/245, 333/127, 333/252, 333/261, 333/243
International ClassificationH01P1/06
Cooperative ClassificationH01P1/068
European ClassificationH01P1/06C2C