Six-port orthomode junction

Abstract

The present invention relates to a six-port orthomode transducer (1) produced by additive manufacturing, and comprising a dual-polarization input port (10); a dual-polarization output port (11); the input port and the output port defining a main direction (100) corresponding to the direction of propagation of a signal between the input port (10) and the output port (11); a first single-polarization side port (12) extending along a first axis (120) transverse to the main direction (100); a second single-polarization side port (13) facing the first side port (12) and extending along a second axis (130) transverse to the main direction (100); a third single-polarization side port (14) extending along a third axis (140) transverse to the main direction (100); a fourth single-polarization side port (15) facing the third side port (14) and extending along a fourth axis (150) transverse to the main direction (100); said first, second, third and fourth transverse axes each forming an angle with the main direction (100) of between 15° and 75°, the six-port orthomode transducer being characterized by a high-pass filter arranged between the side ports and the output port, said high-pass filter comprising at least two filtering slots (21). The present invention also relates to a transceiver antenna comprising such an orthomode transducer and a plurality of low-pass filters.

Description

Six-port orthomode junction Technical field

[0001] The present invention relates to a six-port orthomode transducer suitable for additive manufacturing. State of the art

[0002] In the field of radiofrequency transmissions, dual-polarized antennas are antennas capable of transmitting and receiving electromagnetic waves according to two orthogonal polarizations. These antennas generally consist of a radiating element (typically of the horn type) and a feed chain. This feed chain must in particular allow discrimination of the two orthogonal polarizations so as to be able to combine (in transmission), respectively separate in reception, the two signals. This discrimination can be achieved by means of an orthomode transducer (OMT) with dual polarization such as a "turnstile" junction having an input port connected to the horn and two pairs of side ports placed opposite each other, each pair allowing isolation of one of the polarizations.

[0003] When such an antenna is also dual-band, i.e. capable of operating on two frequency ranges, the feed chain must also be capable of discriminating between the respective frequency ranges. This discrimination is usually achieved by means of band-pass filters arranged in the feed chain.

[0004] Although the operations of separating / combining each polarization on the one hand and filtering the frequencies on the other hand are quite distinct, certain orthomode transducers known in the prior art make it possible to combine the discrimination of polarizations and frequencies. frequencies in a single device. Such devices typically have six ports in total, including an input port and an output port, usually dual-polarized and arranged coaxially, and four side ports, usually single-polarized. Polarization discrimination is performed at the side ports, while frequency band discrimination can be achieved, for example, using a high-pass filter connected to the output port and low-pass filters connected to the side ports.

[0005] However, the recent boom in additive manufacturing in the field of radio frequency transmissions has increased the need to improve the designs of such antennas so that they can be produced by additive manufacturing. In particular, dual-polarized antennas, and orthomode transducers in general, have relatively large overhanging sections, such as lateral waveguides or parts of bandpass filters, making efficient and cheap additive manufacturing impossible. Indeed, the overhanging areas need to be supported during manufacturing, and the supports must then be removed by hand, which generates losses in both time and cost.

[0006] Document US2013 / 0342282 A1 describes a six-port orthomode transducer in which two pairs of rectangular-section side ports are used to discriminate the two orthogonal polarizations of a wave propagating in a main waveguide. The four side ports extend radially relative to the main propagation direction of the signal in the main guide, i.e. perpendicular to this main propagation direction. A low-pass filter is connected to a port of the orthomode transducer whose direction is parallel to the main propagation direction, while four high-pass filters are connected to the four side ports. In this device, the four side ports as well as a low-pass filter as described are not suitable for additive manufacturing for the reasons mentioned above.

[0007] G. Addamo et al., "3D Printing of a Monolithic K / Ka-Band Dual-Circular Polarization Antenna-Feeding Network," in IEEE Access, vol. 9, pp. 88243-88255, 2021, describes a six-port orthomode transducer suitable for additive manufacturing. Frequency discrimination is achieved by a virtual filter consisting of a progressive narrowing of the inner diameter of the main waveguide and by low-pass filters connected to the side ports. The side ports are oriented so that two pairs of side ports form a splitter in the H plane with the input port, i.e., the port intended to be connected to the antenna horn. In other words, the longer side of the side port opening is aligned with the propagation direction. Brief summary of the invention

[0008] An object of the present invention is to provide a six-port orthomode transducer free from the limitations of those known in the prior art.

[0009] Another object of the invention is to provide a six-port orthomode transducer suitable for additive manufacturing.

[0010] Another aim of the invention is to propose a six-port orthomode transducer capable of discriminating between two frequency bands.

[0011] According to the invention, these aims are achieved in particular by means of a six-port orthomode transducer produced by additive manufacturing, and comprising a dual-polarization input port; a dual-polarization output port; the input port and the output port defining a main direction corresponding to the direction of propagation of a signal between the input port and the output port; a first single-polarized lateral port extending along a first axis transverse to the main direction; a second single-polarized lateral port opposite the first lateral port and extending along a second axis transverse to the main direction; a third single-polarized lateral port extending along a third axis transverse to the main direction; a fourth single-polarized lateral port opposite the third lateral port and extending along a fourth axis transverse to the main direction; said first, second, third and fourth transverse axes each forming an angle with the main direction of between 15° and 75°, the six-port orthomode transducer being characterized by a high-pass filter arranged between the lateral ports and the output port, said high-pass filter comprising at least two filtering slots.

[0012] The orthomode transducer may be characterized in that said high-pass filter comprises a platform extending radially from the main direction, the at least two filtering slots being arranged on said platform.

[0013] The platform may include at least one support arch extending radially from the main direction.

[0014] In order to facilitate its additive manufacturing, the at least one support arch may have at least one cantilevered face forming an angle with the main direction of between 15° and 75°.

[0015] The orthomode transducer can be characterized in that a smaller dimension of each of the four side ports is parallel to the main direction.

[0016] The outlet port may include at least one ridge disposed on an inner wall of the outlet port.

[0017] The platform may include a protruding impedance matching element extending in the main direction.

[0018] An inlet port diameter can be larger than an outlet port diameter.

[0019] The orthomode transducer can be characterized by a double symmetry along two mutually orthogonal planes, each of the two orthogonal planes comprising the principal direction.

[0020] The above-mentioned aims are also achieved by means of an antenna for transmitting and / or receiving dual-polarized signals comprising an orthomode transducer as described above and comprising four low-pass filters, each side port being connected to one of the four low-pass filters.

[0021] Each of the four low-pass filters may include at least one inner face provided with slots.

[0022] The antenna can be characterized by a double symmetry along two mutually orthogonal planes, each of the two orthogonal planes comprising the main direction. Brief description of the figures

[0023] Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which:

[0024] Figure 1 illustrates a three-quarter view of a six-port orthomode transducer.

[0025] Figure 2 illustrates a longitudinal section of a six-port orthomode transducer.

[0026] Figure 3 illustrates a longitudinal section of a six-port orthomode transducer.

[0027] Figure 4 illustrates a top view of a six-port orthomode transducer including a filter platform.

[0028] Figure 5a illustrates a filtering platform suitable for additive manufacturing.

[0029] Figure 5b illustrates a top view of a filtering platform suitable for additive manufacturing.

[0030] Figure 6 illustrates a longitudinal section of a filter platform suitable for additive manufacturing.

[0031] Figure 7 illustrates a side section of a dual-polarization diplexer comprising a six-port orthomode transducer and side filters notched on one side.

[0032] Figure 8 illustrates a side section of a dual-polarization diplexer comprising a six-port orthomode transducer and two-sided notched side filters. Example(s) of embodiment of the invention

[0033] Figure 1 illustrates an orthomode transducer 1 according to the invention comprising an input port 10 and an output port 11 with dual polarization determining a main direction 100 corresponding to the direction of propagation of a signal between the input port and the output port. Four lateral ports (12, 13, 14, 15) are connected to the orthomode transducer along four axes transverse to the main direction.

[0034] Throughout the present description, it will be assumed that the orthomode transducer of the present invention is oriented as follows: the main direction of propagation between the input port 10 and the output port corresponds to the z direction which coincides with the 3D printing direction. The x and y directions lie in a plane orthogonal to the z direction and correspond to the orthogonal directions of the polarizations.

[0035] The input port 10 consists of a standard waveguide whose cross-section may be circular, rectangular so as to receive / transmit signals with circular, elliptical or linear polarization. In general, the cross-section of the input port may be any geometric shape deemed suitable by those skilled in the art, including for example pentagonal, hexagonal, polygonal sections with more than six sides, but also combinations of polygon sections with curved sides. In use in a dual-polarization antenna, the input port 10 is typically connected to a waveguide or directly to a radiating element such as a horn. The output port 11 is, for its part, arranged coaxially with the input port 10 and is also dual-polarized.Similarly, the output port 11 is a waveguide whose cross-section may be any geometric shape deemed suitable by those skilled in the art, including, for example, pentagonal, hexagonal, polygonal sections with more than six sides, but also combinations of polygon sections with curved sides.

[0036] Between the input 10 and output 11 ports, the first lateral port 12 extends along a first axis 120 transverse to the main direction 100 and faces the second lateral port 13 which extends along a second axis 130 also transverse to the main direction 100. The first and second ports allow the separation / combination of the signals according to a first polarization P1. The third lateral port 14 extends along a third axis 140 transverse to the main direction 100 and faces the fourth lateral port 15 which extends along a fourth axis 150 transverse to the main direction 100. The third and fourth ports allow the separation / combination of the signals according to a second polarization P2. Each of the four lateral ports is thus single-polarized.

[0037] In an embodiment illustrated in Figure 1 the side ports (12,13,14,15) are of rectangular section with the smallest side of the rectangular sections aligned with the main direction 100, so that the combination of the input port 10 with a pair of opposite side ports (i.e. corresponding to the same polarization) forms a divider / combiner along the plane E. The direction of the electric field of a wave propagated in the two side ports corresponding to the same polarization is therefore opposite.

[0038] As illustrated in Figure 3, each of the first, second, third and fourth axes (120, 130, 140, 150) forms an angle with the main direction 100 of between 15° and 75°, preferably between 35° and 55°. This inclination with respect to the z direction makes additive manufacturing of the side ports possible. Indeed, the z axis generally coincides with the 3D printing direction, thus, the inclination of the side ports with respect to this direction makes it possible to reduce the physical constraints exerted by the force of gravity on these side ports and therefore makes it possible to reduce, or even eliminate, the need for supports during manufacturing. The inclination of the side ports can also make it possible to increase the compactness of the orthomode transducer by limiting its external volume.

[0039] In an embodiment illustrated in Figure 4, the arrangement of the lateral ports (12, 13, 14, 15) as well as the sections of the input 10 and output 11 ports are such that the entire orthomode transducer 1 according to the invention has a double planar symmetry along two mutually orthogonal planes, one of these two planes of symmetry comprising the first and second axes (120, 130) as well as the main direction 100 and the other of these planes of symmetry comprising the third and fourth axes (140, 150) as well as the main direction 100.

[0040] The orthomode transducer 1 of the present invention is provided with a high-pass filter arranged between the side ports and the output port 11. This high-pass filter comprises at least two filter slots 21 for rejecting low frequencies so that only high frequencies can pass through the output port 11.

[0041] In the context of the present invention, the terms "high frequency" and "low frequency" may correspond to different ranges of values ​​depending on the embodiment of the invention. Indeed, the present invention may be implemented in different devices intended for various frequency bands depending on their applications. As examples, the present invention may typically be used in devices intended for the X, Ku, Ka, QV, Ku / ka, and / or Ka / QV bands.

[0042] In X-band, low frequencies are typically between 7.25GHz and 7.75GHz and high frequencies between 7.9GHz and 8.4GHz.

[0043] In Ku band, low frequencies are typically between 10.7GHz and 12.75GHz and high frequencies between 13.25GHz and 4.5GHz, or sub-portions of these particular bands.

[0044] In Ka-band, low frequencies are typically between 17.3GHz and 21.2GHz and high frequencies between 27GHz and 31GHz, or sub-portions of these particular bands.

[0045] In the QV band, low frequencies are typically between 37.5GHz and 42.5GHz and high frequencies between 42.5GHz and 52.5GHz, or sub-portions of these particular bands.

[0046] In the Ku / Ka band, low frequencies are typically between 10.7GHz and 12.75GHz and high frequencies between 13.25GHz and 21GHz, or sub-portions of these particular bands; alternatively, or complementary, low frequencies are typically between 13.25GHz and 21.2GHz and high frequencies between 13.25GHz and 21.2GHz and high frequencies between 27GHz and 31GHz or sub-portions of these particular bands.

[0047] In the Ka / QV band, low frequencies are typically between 27GHz and 42.5GHz and high frequencies between 42.5GHz and 52.5GHz, or sub-portions of these particular bands.

[0048] In one embodiment, the output port 11 has a cross-section with a diameter smaller than the diameter of the cross-section of the input port 10 so that a portion of the frequency band of the input port corresponds to the region below the cut-off frequency of the output port. This reduction in diameter therefore allows for a "virtual" complementary filtering to that of the high-pass filter.

[0049] The low frequencies are propagated in the side ports (12,13,14,15) which can themselves be connected to low-pass filters in order to reject the high frequencies.

[0050] In a preferred embodiment, the high-pass filter comprises a platform 20 in which the filtering slots 21 are arranged. The platform 20 extends radially around the main direction. This platform is illustrated in FIG. 3 and comprises an upper surface facing the inlet port 10 and a lower surface facing the outlet port 11. Preferably, the surface upper part of the platform is perpendicular to the main direction 100.

[0051] The filtering slots 21 may be formed by the platform 20 on the one hand and internal walls of the outlet port 11 on the other hand. Alternatively or additionally, the filtering slots 21 may be formed entirely by the platform 20 in the sense that each side of the slots is formed by a section of the platform.

[0052] In the embodiment illustrated in Figure 4, four triangular filtering slots 21 are formed by the platform 20 on the one hand and the inner walls 110 of the outlet port 11. The platform comprises four arms extending from the main direction 100 towards the inner walls 110 of the outlet port 11.

[0053] The platform 20 may comprise at least one support arch 22 so as to reinforce the stability of the platform during additive manufacturing and / or during use of the orthomode transducer. As illustrated in FIG. 5a, the platform 20 may comprise several support arches 22 meeting at the center of the platform at the main direction.

[0054] In order to facilitate the additive manufacturing of the platform 20 and the support arches 22, the cantilevered faces 220 of the support arches with respect to the z direction form an angle REF with the (z) axis advantageously between 15° and 75°, preferably between 35° and 55°. Figure 6 illustrates a sectional view of the platform in which two support arches 220 form an angle p with the main direction 100. As for the side ports, the optimal inclination in terms of additive manufacturing is around 45°. However, for reasons related for example to the internal geometry of the orthomode transducer, inclinations of the cantilevered faces between 15° and 75° may also be relevant.

[0055] In one embodiment, grooves 23 parallel to the main direction may be arranged on the inner surface of the output port 11. These grooves make it possible, for example, to increase the width of the frequency band and / or to adapt the impedance of the output port 11. As illustrated in FIG. 4, the coupling slots of the high-pass filter may divide the output port into a plurality of waveguides on an inner wall of which a groove 23 may be arranged. The platform 20 may, for example, divide the output port 11 into four waveguides of triangular sections, one side of each section corresponding to the side determined by an inner wall 110 of the output port being provided with a groove 23.

[0056] The platform 20 may also comprise a protruding impedance matching element 24. As illustrated in FIG. 5a, this protruding element may extend in the main direction 100 from the platform 20, the platform thus being able to serve as a support for the protruding element during additive manufacturing.

[0057] The orthomode transducer 1 is typically used in the feed chain of a radiofrequency antenna further comprising an antenna horn connected to the input port 11. Such an antenna also generally comprises low-pass filters 30 connected to the side ports (12, 13, 14, 15).

[0058] Figure 7 illustrates in section an embodiment in which each side port is connected to a low-pass filter 30, for example a low-pass filter notched on a side wall. Each of the low-pass filters extends along the main direction 100. The filters are advantageously symmetrical along the two planes of symmetry mentioned above, that is to say along a plane comprising the main direction 100 as well as the first and second transverse axes (120, 130), and along another plane comprising the main direction 100 as well as the third and fourth transverse axes (140, 150). The orthomode transducer and low-pass filter assembly thus retains a double planar symmetry.

[0059] Figure 8 illustrates an embodiment in which the low-pass filters 30 connected to the side ports have two crenellated internal walls. These filters 30 also extend along the main direction 100. Again, a double symmetry of the orthomode transducer and low-pass filter assembly can be obtained.

[0060] In a feed chain comprising an orthomode transducer according to the present invention as well as low-pass filters as described above, the two pairs of low-pass filters corresponding to the first and second polarizations can then be recombined using two single-band combiners. In such a feed chain, the output port can also be connected to a single-band orthomode transducer. Advantageously, the single-band combiners and the single-band orthomode transducer are also arranged so as to preserve the double symmetry of the feed chain. Reference numbers used in the figures Orthomode transducer Port of entry Main management Output port Inner wall of the outlet port First side port Second side port Third side port Fourth lateral port First transverse axis Second transverse axis Third transverse axis Fourth transverse axis Platform Filter slot Support arch Cantilevered face Streak Impedance matching salient element Low-pass filter

Claims

Claims 1. A six-port orthomode transducer (1) produced by additive manufacturing, and comprising a dual-polarization input port (10); a dual-polarization output port (11); the input port and the output port defining a main direction (100) corresponding to the direction of propagation of a signal between the input port (10) and the output port (11); a first single-polarization lateral port (12) extending along a first axis transverse (120) to the main direction (100); a second single-polarization lateral port (13) opposite the first lateral port (12) and extending along a second axis transverse (130) to the main direction (100); a third single-polarization lateral port (14) extending along a third axis transverse (140) to the main direction (100);a fourth lateral port (15) with single polarization opposite the third lateral port (14) and extending along a fourth transverse axis (150) to the main direction (100); said first, second, third and fourth transverse axes each forming an angle with the main direction (100) of between 15° and 75°, the six-port orthomode transducer being characterized by a high-pass filter arranged between the lateral ports and the output port, said high-pass filter comprising at least two filtering slots (21).; 2. Orthomode transducer (1) according to claim 1, characterized in that said high-pass filter comprises a platform (20) extending radially from the main direction (100), the at least two filtering slots (21) being arranged on said platform.

3. Orthomode transducer (1) according to claim 2, said platform (20) comprising at least one support arch (22) extending radially from the main direction (100).

4. Orthomode transducer (1) according to claim 3, the at least one support arch (22) having at least one cantilevered face (220) forming an angle (p) with the main direction (100) of between 15° and 75°.

5. Orthomode transducer (1) according to one of the preceding claims, characterized in that a smaller dimension of each of the four lateral ports (12,13,14,15) is parallel to the main direction (100).

6. Orthomode transducer (1) according to one of the preceding claims, the output port (11) comprising at least one groove (23) arranged on an internal wall (110) of the output port.

7. Orthomode transducer (1) according to one of claims 2 to 6 if it depends on claim 2, the platform (20) comprising a projecting impedance matching element (24).

8. Orthomode transducer (1) according to one of the preceding claims, a diameter of the input port (10) being greater than a diameter of the output port (11).

9. Orthomode transducer (1) according to one of the preceding claims being characterized by a double symmetry along two planes orthogonal to each other, each of the two orthogonal planes comprising the main direction (100).

10. Antenna for transmitting and / or receiving dual-polarized signals comprising an orthomode transducer (1) according to one of the preceding claims and comprising four low-pass filters (30), each side port (12,13,14,15) being connected to one of the four low-pass filters (30).

11. Antenna according to claim 10, each of the four low-pass filters (30) comprising at least one internal face provided with crenellations.

12. Antenna according to one of claims 10 to 11 being characterized by a double symmetry along two planes orthogonal to each other, each of the two orthogonal planes comprising the main direction (100).

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