Rotary Joint with Dielectric Waveguide

Abstract

A contactless datalink for transmission of data between a rotatable part and a stationary part, including a dielectric waveguide split into two sections. A first dielectric waveguide section is at the rotatable part and a second dielectric waveguide section is at the stationary part. The first dielectric waveguide section is coupled to a transmitter and the second dielectric waveguide section is coupled to a receiver.

Claims

1. A contactless datalink configured to transmit data between a stationary part and a rotatable part and configured to rotate around an axis of rotation, the datalink comprising a ring-shaped dielectric waveguide, the ring-shaped dielectric waveguide including a first dielectric waveguide component at the rotatable part and a second dielectric waveguide component at the stationary part, the ring-shaped dielectric waveguide having a center axis aligned with the axis of rotation, the ring-shaped dielectric waveguide having a gap between the first dielectric waveguide component and the second dielectric waveguide component, the first dielectric waveguide component including at least one rotatable waveguide section, the at least one t rotatable waveguide section having two ends wherein one end is connected to at least one of a first transmitter, a first receiver, and a first absorber and the other end is connected to at least one of a second transmitter, a second receiver, and a second absorber, the second dielectric waveguide component includes at least one stationary waveguide section, the at least one stationary waveguide section having two ends wherein one end is connected to at least one of a third transmitter, a third receiver, and a third absorber and the other end is connected to at least one of a fourth transmitter, a fourth receiver, and a fourth absorber.

2. The contactless datalink of claim 1, wherein the first dielectric waveguide component includes a first rotatable waveguide section and a second rotatable waveguide section, wherein first ends of the first and second rotatable waveguide sections that are close together are connected via a 3 dB coupler to a transmitter, from the first and second transmitter, and second ends of the first and second rotatable waveguide section are terminated by the first and second absorbers; and wherein the second dielectric waveguide component includes a first stationary waveguide section and a second stationary waveguide section, wherein first ends of the first and second stationary sections that are close together are connected via a 3 dB coupler to a transmitter, from the third and fourth transmitters, and second ends of the first and second stationary sections are terminated by the third and fourth absorbers.

3. The contactless datalink of claim 1, wherein the first dielectric waveguide component includes a first rotatable waveguide section and a second rotatable waveguide section, wherein first ends of the first and second rotatable sections are disposed close together and second ends of the first and second rotatable sections are disposed close together; the first end of the first rotatable waveguide section and the second end of the second rotatable waveguide section are connected by a first 3 dB coupler to a transmitter, from the first and second transmitters; the second end of the first rotatable waveguide section and the first end of the second rotatable waveguide section are connected by a second 3 dB coupler to a receiver, from the first and second receivers; the second dielectric waveguide component includes a first stationary waveguide section and a second stationary waveguide section, wherein first ends of the first and second stationary sections are disposed close together and second ends of the first and second stationary sections are disposed close together; the first end of the first stationary waveguide section is connected to a receiver, from the third and fourth receivers, and the first end of the second stationary waveguide section is connected to a transmitter, from the third and fourth transmitters; and the second ends of the first and second stationary sections are terminated by the third and fourth absorbers.

4. The contactless datalink of claim 1, wherein one end of said at least one rotatable waveguide section is connected to a transmitter, from the first and second transmitters, and the other end of said at least one rotatable waveguide section is connected to a receiver, from the first and second receivers; and wherein one end of said stationary waveguide section is connected to a transmitter, from the third and fourth transmitters, and the other end of said stationary waveguide section is connected to a receiver, from the third and fourth receivers.

5. The contactless datalink of claim 1, wherein the at least one rotatable waveguide section is coupled to a transmitter, from the first and second transmitters, and the at least one stationary swaveguie section is coupled to a receiver, from the third and fourth receivers.

6. The contactless datalink of claim 1, wherein the first dielectric waveguide component has a structure identical to a structure of the second dielectric waveguide component.

7. The contactless datalink of claim 1, wherein a width of a gap between the first and second dielectric waveguide components is in a range of 1/10th to th of a wavelength of a signal wave to be transmitted in air.

8. The contactless datalink of claim 1, wherein at least one of the following conditions is satisfied: the at least one rotatable waveguide section includes multiple rotatable waveguide section having equal lengths and the at least one stationary waveguide section includes multiple stationary waveguide section having equal lengths.

9. A contactless datalink configured to transmit data between a rotatable part and a stationary part, the datalink comprising: a closed-loop dielectric waveguide, at least one stationary coupler, at least one rotatable coupler, at least one stationary transceiver coupled to the at least one stationary coupler, and at least one rotatable transceiver coupled to the at least one rotatable coupler.

10. The contactless datalink of claim 9, wherein the at least one stationary coupler includes a pair of stationary waveguide couplers the at least one rotatable coupler includes a pair of rotatable waveguide couplers, and wherein one of the following conditions is satisfied: a) first and second couplers from each of the pair of stationary waveguide couplers and the pair of rotatable waveguide couplers are connected to a respectively-corresponding transceiver, from the at least one stationary transceiver and the at least one rotatable transceiver, at first ends of said first and second couplers that are disposed close to one another; and b) said first and second couplers are connected to the respectively-corresponding transceiver at second ends of said first and second couplers that are separated from one another by at least a length of a coupler from the first and second couplers.

11. The contactless datalink of claim 9, wherein the at least one rotatable transceiver has at least two RF ports, the at least one stationary transceiver has at least two RF ports, wherein said link includes more than one closed-loop waveguides that are configured to transmit data in parallel, wherein the at least one stationary transceiver that is coupled to the at least one stationary coupler and at the least one rotatable transceiver that is coupled to the at least one rotatable coupler are connected to a corresponding of said multiple closed-loop waveguides.

12. The contactless datalink of claim 9, wherein the at least one rotatable transceiver has at least one RF port configured to separately optimize at least one of transmission quality and data rate by controlling carrier frequency, phase, amplitude and modulation parameters to establish a communication to any one or more RF ports of the at least one stationary transceiver to separately match changing attenuation and phase during rotation and to avoid crosstalk between corresponding RF ports of either of the at least one rotatable transceiver and the at least one stationary transceiver.

13. The contactless datalink of claim 9, wherein the at least one rotatable transceiver has two or more RF ports configured to separately optimize at least one of transmission quality and data rate by controlling carrier frequency, phase, amplitude and modulation parameters y to any two or more RF ports of the at least one stationary transceiver to separately match changing attenuation and phase during the rotation and to avoid crosstalk between the RF ports of either of the at least one rotatable transceiver and the at least one stationary transceiver and to establish multiple parallel communication channels during all times.

14. The contactless datalink of claim 9, configured to operate at an operating frequency within the EHF band.

15. The contactless datalink of claim 9, configured to operate at an operating frequency between 2.4 GHz and 30 GHz.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In the following, the invention will be described by way of example, without limitation of the general inventive concept, on examples of embodiment and with reference to the drawings.

[0032] FIG. 1a, 1b, 1c present different modifications of an embodiment of a dielectric waveguide.

[0033] FIG. 2 presents a basic embodiment of a single channel unidirectional data communication.

[0034] FIG. 3 illustrates a further embodiment of a single channel bidirectional data communication.

[0035] FIG. 4 shows a related embodiment of a multichannel bidirectional data communication.

[0036] FIG. 5 presents a further embodiment of a multichannel bidirectional data communication.

[0037] FIG. 6 depicts a further embodiment.

[0038] FIG. 7 presents a basic concept of a further dielectric waveguide in a sectional view.

[0039] FIG. 8 presents schematically a CT (Computed Tomography) scanner gantry.

[0040] FIG. 9 presents a further bidirectional embodiment employing transceivers.

[0041] FIG. 10 illustrates a further bidirectional embodiment employing transceivers.

[0042] FIG. 11 presents a further bidirectional embodiment employing transceivers.

[0043] Generally, the drawings are not to scale. Like elements and components are referred to by like labels and numerals. For the simplicity of illustrations, not all elements and components depicted and labeled in one drawing are necessarily labels in another drawing even if these elements and components appear in such other drawing.

[0044] While various modifications and alternative forms, of implementation of the idea of the invention are within the scope of the invention, specific embodiments thereof are shown by way of example in the drawings and are described below in detail. It should be understood, however, that the drawings and related detailed description are not intended to limit the implementation of the idea of the invention to the particular form disclosed in this application, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.

DETAILED DESCRIPTION

[0045] FIG. 1a illustrates a first embodiment of the waveguide structure, showing a portion of the dielectric waveguide 100. The dielectric waveguide 100 includes two waveguide components, preferably two identical and/or symmetrically-disposed components 101 and 102, forming a disc configuration. One component, for example, a first component 101 is mounted at the stationary part of the device, and a second component 102 is mounted at the rotatable part. The dielectric waveguide components may together (when considered combined) form a substantially round cross-section (as shown in FIG. 1a), or an oval or rectangular cross-section in the alternative. Notably, in an embodiment the rotatable and stationary parts to which the components 1-2. 102 are mounted may be exchanged. There is generally left a gap 107 between the two components along a plane 109 that may be orthogonal to the rotation axis 108.

[0046] As shown in FIG. 1b, in a related embodiment of the waveguide structure, the ring waveguide including a first dielectric waveguide component 103 and a second dielectric waveguide component 104 may be formed such that the gap between these waveguide components 103, 104 is formed in a plane that, while being transverse to the rotation axis 108, is not exactly perpendicular to the axis 108 (as shown, the plane of the gap intersects the axis 108 at an angle, such as a slanted angle or a 45 degrees angle). In another embodiment, the ring including a first dielectric waveguide component 105 and a second dielectric waveguide component 106 may be split into two waveguide components 106, 107 (that is, formed by these two component) as shown in FIG. 1c along a cylindrical surface substantially parallel to the rotation axis to thereby form a drum configuration.

[0047] Any of the above-presented configurations allows for coupling of signals from either side to the other side.

[0048] In FIG. 2, a basic embodiment of the waveguide-containing portion of the device is shown, which may be based on a waveguide structure of the first embodiment of FIG. 1a. Here, a stationary waveguide (131, 132) including a first section 131 and a second section 132 is at a first part of the device. The rotatable waveguide of the devicethe waveguide (133, 134)also has a corresponding first section 133 and a corresponding second section 134. The stationary waveguide and the rotatable waveguide of the embodiment of FIG. 2 are in close contact with each other such that signals are easily coupled between the stationary and rotatable waveguides (131,132) and (133,134), preferably in both directionsfrom the stationary waveguide to the rotatable waveguide and from the rotatable waveguides to the stationary waveguides. Preferably, all waveguide sections 131, 132, 133, 134 have approximately the same lengths, and therefore cover about half the circumference of the corresponding rotational or stationary part, corresponding to an angular extent of approximately 180 degrees. The waveguide sections preferably have two ends. The first stationary waveguide section 131 and the second stationary waveguide section 132 are connected with their two ends that are close together (neighboring each other) to a 3 dB coupler 142, which is further coupled to a receiver 141. The coupler 142 is configured to combine, in operation, the signals from both stationary waveguide sections 121, 132 and forward these to the receiver 141. The opposing ends of the waveguide sections 131, 132 are coupled to absorbers 143 and 144. The rotatable waveguide sections 133 and 134 are connected with their ends that are close together to a 3 dB coupler 152, which is further connected to a transmitter 151. In operation, the signal from the transmitter 151 are forwarded to the 3 dB coupler 152, which splits such signal into two substantially equal signals that are then fed into each of the rotatable waveguide sections 133 and 134. The opposing ends of the rotatable waveguide sections are also terminated by absorbers 153 and 154.

[0049] Preferably, the transmitter 151 is configured to generate and modulate RF signals in the range of and above 60 GHz, and to couple a wave at such frequency(ies) into the dielectric waveguide, where the wave propagates towards the receiver 141.

[0050] In FIG. 3, a related embodiment is schematically shown. Here, the curved stationary waveguide sections 131 and 132 are connected (at positions close to each other) with a transmitter 164 and a receiver 161, such that the first stationary waveguide section 131 is connected to the receiver 161, and the second stationary waveguide section 132 is connected to the transmitter 164. The first rotatable waveguide section 133, on the other hand, is connected at uts first end with a first 3 dB coupler 172, which is further connected to a receiver 171. The second end of the waveguide section 133 is connected to a second 3 dB coupler 174, which is further connected to a transmitter 173. Further, viewed in a clockwise direction, the first end of the second rotatable waveguide section 134 is connected to the first 3 dB coupler 172, whereas the second end of the second rotatable waveguide 134 is connected to the second 3 dB coupler 174. This criss-cross connection allows for a signal transmission without change in phase. The angular gap between the ends of line prevents cross-coupling between the ends of the rotatable waveguide sections 133 and 134.

[0051] In FIG. 4, yet another related embodiment is shown with only one first waveguide 131 and one second waveguide 133. The first waveguide 131 is connected at one end to a receiver 182 and at the opposing end to a transmitter 181. The second waveguide 133 is connected at a first to a receiver 192 and at the opposing end to a transmitter 191. The link is structured such that transmitter and receiver are arranged opposite to one another as far as the directions of propagations of the signals is concerned. A spatial gap between receiver and transmitter causes a high signal attenuation between receiver and transmitter.

[0052] Alternatively, and in a related embodiment, to arrive at a configuration somewhat similar to that of FIG. 4, the ends of the two stationary waveguide sections (each covering approximately half of the circumference of the stationary part of the device) can be joined to a single waveguide 131, the free ends of which are then connected to the transceiver combining receiver 182 and transmitter 181, respectively. At the same time, the ends of the two rotatable waveguide sections (each covering approximately half of the circumference of the rotatable part o the device) can be joined to a single waveguide 133, the free ends of which are then connected to the transceiver combining receiver 192 and transmitter 191.

[0053] In FIG. 5, a further embodiment is shown, where the stationary waveguide includes a first stationary waveguide section 131 and a second stationary waveguide section 132 (which have substantially the same lengths and therefore have an angular extend of about 180 degrees each). The rotatable waveguide includes a first rotatable waveguide section 133, a second rotatable waveguide section 134, and a third rotatable waveguide section 135 (which all have about the same size, and therefore cover corresponding angles of about 120 degrees). The first stationary waveguide section 131 is connected at a first end to a receiver 201 and to a transmitter 202 at the opposing end. As viewed clockwise next to this end, the first end of the second stationary waveguide section 132 is connected to a receiver 203, and the opposing end to a transmitter 204. Therefore, transmitters and receivers present in this embodiment are alternatingly connected at the ends of the sections of the first stationary waveguide, such that a receiver is followed by a transmitter in a clockwise view. At the rotatable waveguide sections 133, 134, 15, there is basically the same arrangement, such that a transmitter is followed by a receiver in a clockwise view on each of the three sections. Therefore, the first rotatable waveguide section 133 has a receiver 211 at a first end thereof and opposing thereto a transmitter 212. Next to it, the second rotatable waveguide section 134 has a receiver 213 at its first end and a transmitter 214 at its second end. This is followed by the third rotatable waveguide section having a receiver 215 at its first end and a transmitter 216 at its second end. The second end of the third rotatable waveguide section 135 with the transmitter 216 is disposed close to the first end of the first rotatable waveguide section 133 with the receiver 211. In a related embodiment, the sequence of transmitters and receivers may be reversed.

[0054] Also, one end of the first stationary waveguide section 131 and 132 can be joined together to form a single (loop) waveguide connected, on one hand, to a transceiver device that combines the receiver 203 and the transmitter 202, on the other hand, to another transceiver device combining the receiver 201 and the transmitter 204. Also, receiver 213 and transmitter 212, receiver 215 and transmitter 214 and receiver 211 and transmitter 216 can be paired to transceivers.

[0055] In FIG. 6, a further embodiment is shown. A first part, for example the stationary part, may bear stationary waveguide sections 131, 132. A second part, for example a rotatable part, may bear rotating waveguide sections 133, 134, 135, 136 which all have about the same size, and therefore cover angles of about 90 degrees each. The stationary waveguides 131, 132 have receivers 112, 114 at their first ends and transmitters 111, 113 at their second ends. Accordingly, in the clockwise direction, first waveguide 131 has a receiver 114 at its first end and a transmitter 111 at its second end, whereas the first waveguide 132 has a receiver 112 at its first end and a transmitter 113 at its second end.

[0056] Each of the rotatable waveguides have either a transmitter or a receiver at one end, and an absorber at the opposing end. Here, the first rotatable waveguide 133 is show to have, as viewed in a clockwise direction, at its first end a receiver 121 and an absorber 122 opposing thereto. The second rotatable waveguide section 134 has an absorber 123 at an end close to the absorber 122 and a transmitter 124 opposing thereto. The third rotatable waveguide section 135 has a receiver 125 close to the transmitter 124 and opposing thereto an absorber 126. The fourth rotatable waveguide section 136 has an absorber 127 close to the absorber 1226 and opposing thereto a transmitter 128.

[0057] The function and, therefore, positioning of the rotatable and the stationary parts may be exchanged. Furthermore, the orientation of the transmitters or receivers may be exchanged with respect to the waveguides. In any case, in each of the embodiments, each of the transmitters may be exchanged by a receiver, and each of the receivers may be exchanged by a transmitter.

[0058] All transmitters and receivers shown in FIGS. 4, 5, and 6 as well as receiver 161 and transmitter 164 in FIG. 3 may be combined to a transceiver when both half waveguides are combined to a full waveguide in direct vicinity of the transceivers.

[0059] In FIG. 7, a basic concept of a further dielectric waveguide embodiment 300 is shown in a sectional view. The waveguide has a dielectric core 301 and a metallic shield 302, which has a gap 303. For coupling a signal, there may be a pickup 310 that preferably has only a short length of few millimeters or few centimeters (as compared to the total length of the dielectric waveguide, which may be in the range of several meters). The embodiment is configured to ensure that energy may only be radiated out of the gap at a position where the pickup is located, as there the impedance should be matched.

[0060] FIG. 8 shows schematically a CT (Computed Tomography) scanner gantry. The stationary part is suspended within and is part of a massive frame 810. The rotatable part 809 of the gantry is rotatably mounted with respect to the stationary part and rotates along the rotation direction 808. It supports an X-ray tube 801 for generating an X-ray beam 802 that radiates through a patient 804 lying on a table 807 and which is intercepted by a detector 803 and converted to electrical signals and imaging data thereof. Electrical power from power supply unit 811 may be transmitted by a slipring (not shown) to the rotatable part. The data obtained by the detector 803 are transmitted via contactless rotary joint 800 to an evaluation unit 806 by means of a data bus or network 805.

[0061] In the following description of FIGS. 9, 10, 11, the closed-loop dielectric waveguide 400 is considered, but referred to as waveguide 400 of waveguide structure 400, for simplicity of presentation.

[0062] In FIG. 9, an embodiment is shown which may be based on a standard dielectric waveguide structure 400 that is dimensioned to form a closed loop and that includes one part that is conformed to a circle (where either both ends of the waveguide are glued or welded together or where such waveguide is initially configured as a circular loop, as one part). This circular dielectric waveguide might be fixed to the stator (stationary part) or fixed to the rotor (rotatable part). The cross-section of the waveguide 400 might be shaped circularly, ellipticly, as an oval, or rectangularly, or \have any other shape suited to guide a target wave.

[0063] Also, this waveguide 400 might be substantially identical to one waveguide section 101 as described in FIG. 1, that means it is only one section of a dielectric waveguide split into two sections where either section can guide a wave but also the combined sections.

[0064] Two couplers (420, 440) formed of a standard dielectric waveguide as described may be used to couple a wave in and/or out of the waveguide 400. These couplers are kept in close distance preferably in the range of th to 1/10.sup.th of a wavelength in air, the distance may vary because of mechanical tolerances between near zero and up to .sup.th of a wavelength. The couplers preferably are mounted as circular segments having the same center point as the waveguide 400. The lengths of each of the two couplers preferably are substantially identical and are shorter than half of the total circumference.

[0065] The waveguide 400 might also be configured to rotate at a different speed than that of the rotatable coupler. Since in an embodiment, the waveguide 400 is configured as either rotatable or stationary waveguide, one of the couplers might be mounted in a fixed position and distance to the waveguide 400. The rotatable coupler 440 is mounted in such a way that it cannot collide with the stationary coupler during rotation. This means that one coupler (e.g. the stationary coupler 420 as in this figure) can be mounted on the inner side of the waveguide 400, the other coupler (e.g. the rotatable coupler 440 as in this Figure) on the outer diameter. Alternatively, the couplers can be mounted before or behind the waveguide 400 or at any angular disposition where a collision is avoided.

[0066] One or both of the couplers 420, 440 can also be part of a waveguide section 102 as described in FIG. 1, that means that the coupler is formed of a part of the other section of a waveguide split into two sections where either section can guide a wave but also the combined sections. Preferably this is the rotatable coupler 440 when the waveguide 400 is stationary.

[0067] The transceivers 410, 430 include a transmitter and receiver that are connected to one port of the transceiver for wireless transmission and reception of. This port can also be used for wired communication through a dielectric waveguide if the port is coupled to a dielectric waveguide capable to guide the wave. The stationary transceiver 410 having one port to transmit and receive signals wireless and is connected to the stationary coupler 420 either by a connecting dielectric waveguide or by directly coupling a wave into the coupler e.g. by an antennaor by a coaxial cable connecting the transceiver to an antenna which then couples the signal into the coupler. The stationary transceiver 410 has one port to transmit and receive signals wirelessly and is connected to the stationary coupler 420. (Similarly, the rotatable transceiver 430 has one port to transmit and receive signals wirelessly and is connect to the rotatable coupler 440.) The waveguide 400 and couplers 420, 440 that are also formed of waveguides as described, are in close contact with each other such that signals are operably coupled between the stationary and rotatable couplers with the waveguide 400 in between, preferably in both directions.

[0068] In the configuration described in this FIG. 9 data transmitted up (from stationary transceiver 410 to rotary transceiver 430) are propagating as waves in the waveguide 400 in clockwise direction, the data transmitted down (from rotary transceiver 430 to stationary transceiver 410) are propagating in the counter-clockwise direction. Preferably the waveguide 400 has an attenuation low enough to allow communication between the both transceivers during a first round of the waves travelling but high enough not to distort the receiver after the first round is completed

[0069] Preferably, the stationary transceiver 410 generates and modulates RF signals in the range of and above 60 GHz and couples a wave into the dielectric waveguide where it propagates towards the rotary transceiver 430 and vice versa. The technology can also be used with all carrier frequencies that can be coupled into dielectric waveguides, e.g. operating at 2.4 GHz or 5 GHz or any frequency above that but below optical frequencies.

[0070] Both transceivers have a another wired port that is not shown which is electrically coupled to transmit and receive data via a bus. The waveguide 400 and the couplers 410, 430 form a contactless rotary joint for bidirectional data transmission. In case of the CT gantry shown and described in FIG. 8. The data obtained by the detector 803 of FIG. 8 is transmitted via the rotatable transceiver 430 through the contactless rotary joint described in FIG. 9 to the stationary transceiver which is connected by bus (not shown) to the stationary evaluation unit 806 of FIG. 8 where the data are received, control data are transmitted in the opposite direction.

[0071] FIG. 10 illustrates the same principle setup of rotatable couplers and waveguide 400 as in FIG. 9. The difference between the embodiments of FIG. 10 and FIG. 9 is that in FIG. 10 a multiport transceiver 411 with at least a first stationary port 412 and at least a second stationary port 413 is configured to optimize transmission quality and/or data rate by controlling carrier frequency, phase, amplitude and modulation parameters of each of these RF porst to separately match changing attenuation and phase during the rotation and to avoid crosstalk between the channels of the transceiver 411; and a multiport transceiver 431 with at least a first rotatable port 432 and at least a second rotatable port 433 is configured to optimize transmission quality and/or data rate by controlling carrier frequency, phase, amplitude and modulation parameters of each of these RF ports to separately match changing attenuation and phase during the rotation and to avoid crosstalk between the channels of the transceiver 431.

[0072] In the configuration described data transmitted up (from stationary multiport transceiver 411 to rotary/rotatable multiport transceiver 431) are propagating as modulated waves in the waveguide in clockwise direction, the data transmitted down (from rotary multiport transceiver 431 to stationary transceiver 411) are propagating in the contrary direction. Preferably the waveguide 400 has an attenuation low enough to allow communication between the both transceivers during a first half round of the waves travelling but high enough not to distort the receiver after the first round is completed

[0073] In this configuration, the first stationary port 412 and the second stationary port 413 of the stationary multiport transceiver 411 communicate via first stationary coupler 421, second stationary coupler 422, waveguide 400 and first rotatable coupler 441, second rotatable coupler 442 with the first rotatable port 432 and the second rotatable port 433 of the rotatable multiport transceiver 431. The transceivers select as inputs the RF port with the best communication quality, which changes during rotation, typically determined by bit error rate. To optimize the transmission by lowering the crosstalk between the channels the first and second rotatable couplers 441,442 may be positioned approximately 180 degrees apart of each other. The same applies for the first and second rotatable couplers 441,442 which preferably are positioned approximately 180 degrees apart of each other. With n (n=1, 2, 3, 4, 5, . . . ) ports the displacement of the couplers should be approximately 360 degrees divided by n. FIG. 10 shows a displacement of approximately 90 degrees. Here, the stationary waveguide couplers 421, 422 are shown connected to the stationary transceiver 411 and the ends of these two couplers that are separated from one another at least by a length of one of these two couplers. Similarly the rotatable waveguide couplers 441, 442 are shown connected to the rotatable transceiver 431 at the ends of these two couplers that are separated from one another at least by a length of one of these two couplers.

[0074] Preferably the transceivers are employing the MIMO (multiple in-multiple out) technology as e.g. defined in recent substandards of IEEE-802.11-(WiFi/WLAN-Standard) e.g. IEEE-802.11n and newer substandards-(WiFi/WLAN-Standard). Another implementation into a widely used commercial standard is LTE at e.g. 2.6 GHz. These standards for wireless communication optimize by allowing any port of one transceiver to communicate with any port of the corresponding transceiver. FIG. 11 is similar to FIG. 10.

[0075] In the configuration port the first stationary port 412 of the stationary multiport transceiver 411 communicates via stationary coupler 421, waveguide 400 and rotatable coupler 441 with port the first rotatable port 432 of the rotatable multiport transceiver 431, the second stationary port 413 of the stationary multiport transceiver 411 communicates via stationary coupler 421, waveguide 400 and rotatable coupler 441 with the second rotatable port 433 of the rotatable multiport transceiver 431.

[0076] Here preferably the closed loop waveguide 400 has an attenuation low enough to allow communication between the both transceivers during a first half round of the waves travelling but high enough not to distort the receiver after the first round is completed. To optimize the transmission the first and second rotatable couplers 441, 442 may be positioned approximately 180 degrees apart of each other. The same applies for the first and second rotatable couplers 441, 442 which may be positioned approximately 180 degrees apart of each other. With n (n=1, 2, 3, 4, 5, . . . ) ports the displacement of the couplers should be approximately 360 degrees divided by n. FIG. 11 shows a displacement of approximately 90 degrees. Here, the stationary waveguide couplers 421, 422 are shown connected to the stationary transceiver 411 and the ends of these two couplers that are located close to one another. Similarly the rotatable waveguide couplers 441, 442 are shown connected to the rotatable transceiver 431 at the ends of these two couplers that are located close to one another.

[0077] It will be appreciated to those skilled in the art having the benefit of this disclosure that this invention is believed to provide contactless datalinks between rotatable parts. Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.

LIST OF REFERENCE NUMERALS

[0078] 100 ring shaped dielectric waveguide [0079] 101 first dielectric waveguide component [0080] 102 second dielectric waveguide component [0081] 103 first dielectric waveguide component [0082] 104 second dielectric waveguide component [0083] 105 first dielectric waveguide component [0084] 106 second dielectric waveguide component [0085] 107 gap [0086] 108 rotation axis [0087] 109 plane [0088] 111 transmitter [0089] 112 receivers [0090] 113 transmitter [0091] 114 receivers [0092] 121 receiver [0093] 122 absorber [0094] 123 absorber [0095] 124 transmitter [0096] 125 receiver [0097] 126 absorber [0098] 127 absorber [0099] 128 transmitter [0100] 131 first stationary waveguide section [0101] 132 second stationary waveguide section [0102] 133 first rotatable waveguide section [0103] 134 second rotatable waveguide section [0104] 135 third rotatable waveguide section [0105] 136 fourth rotatable waveguide section [0106] 141 receiver [0107] 142 3 dB coupler [0108] 143 absorber [0109] 144 absorber [0110] 151 transmitter [0111] 152 3 dB coupler [0112] 153 absorber [0113] 154 absorber [0114] 161 transmitter [0115] 164 receiver [0116] 171 receiver [0117] 172 first 3 dB coupler [0118] 173 transmitter [0119] 174 second 3 dB coupler [0120] 181 transmitter [0121] 182 receiver [0122] 191 transmitter [0123] 192 receiver [0124] 201 receiver [0125] 202 transmitter [0126] 203 receiver [0127] 204 transmitter [0128] 211 receiver [0129] 212 transmitter [0130] 213 receiver [0131] 214 transmitter [0132] 215 receiver [0133] 216 transmitter [0134] 300 dielectric waveguide [0135] 301 dielectric core [0136] 302 metallic shield [0137] 303 gap [0138] 310 pickup [0139] 400 closed loop dielectric waveguide [0140] 410 stationary transceiver [0141] 411 stationary multiport transceiver [0142] 412 first stationary port [0143] 413 second stationary port [0144] 420 stationary coupler [0145] 421 first stationary coupler [0146] 422 second stationary coupler [0147] 430 rotatable transceiver [0148] 431 rotatable multiport transceiver [0149] 432 first rotatable port [0150] 433 second rotatable port [0151] 440 rotatable coupler [0152] 441 first rotatable coupler [0153] 442 second rotatable coupler [0154] 800 contactless rotary joint [0155] 801 x-ray tube [0156] 802 x-ray beam [0157] 803 x-ray detector [0158] 804 patient [0159] 805 network [0160] 806 evaluation unit [0161] 807 patient table [0162] 808 rotation direction [0163] 809 rotatable part [0164] 810 frame [0165] 811 power supply unit