Six-port orthomode junction

Abstract

The present invention relates to a six-port orthomode transducer (1) manufactured by additive manufacturing, comprising a dual-polarized input port (10); a dual-polarized output port (11); a first single-polarized side port (12); a second single-polarized side port (13); a third single-polarized side port (14); and a fourth single-polarized side port (15), said side ports extending along a first transverse axis (120) to the principal direction (100). The six-port orthomode transducer is characterized by a high-pass filter disposed between the side ports and the output port, said high-pass filter comprising at least two filter slots (21). The present invention also relates to a transmit / receive antenna comprising such an orthomode transducer and a plurality of low-pass filters. Figure to be published with the abstract: Figure 2

Description

Title of invention: 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-polarization antennas are antennas capable of transmitting as well as receiving electromagnetic waves according to two orthogonal polarizations. These antennas are generally made up 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 (English acronym "OMT") with dual polarization such as a "turnstile" junction having an input port connected to the horn and two pairs of lateral ports placed one opposite the other, each pair making it possible to isolate 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 the respective frequency ranges. This discrimination is usually carried out 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 in a single device. Such devices generally comprise six ports in all, including an input port and an output port generally with dual polarization and arranged coaxially, as well as four lateral ports, generally with single polarization. The discrimination of the polarizations is carried out at the lateral ports while the discrimination of the frequency bands can be carried out for example using a high-pass filter connected to the output port and low-pass filters connected to the lateral ports.

[0005] However, the recent boom in additive manufacturing in the field of radio frequency transmissions has seen an increase in the need to improve the designs of such antennas so that they can be produced by additive manufacturing. In particular, dual-polarization antennas, and orthomode transducers in general, have relatively large overhanging sections, such as lateral waveguides or certain 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 terms of both time and cost.

[0006] Document US2013 / 0342282 A1 describes a six-port orthomode transducer in which two pairs of rectangular-section lateral ports make it possible to discriminate the two orthogonal polarizations of a wave propagating in a main waveguide. The four lateral 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 one 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 on the one hand by a virtual filter consisting of a progressive narrowing of the inner diameter of the main waveguide and on the other hand by low-pass filters connected to the side ports. The side ports are oriented so that two pairs of side ports form, together with the input port, i.e., the port intended to be connected to the antenna horn, a splitter in the H plane. In other words, the longer side of the opening of the side ports 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 propose a six-port orthomode transducer suitable for additive manufacturing.

[0010] Another object of the invention is to propose a six-port orthomode transducer making it possible to discriminate 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

[0012] a dual-polarization input port; a dual-polarized output port; the input port and the output port defining a corresponding main direction to the direction of propagation of a signal between the input port and the output port;

[0013] a first single-polarization lateral port extending along a first axis transverse to the main direction;

[0014] a second single-polarization lateral port opposite the first lateral port and extending along a second axis transverse to the main direction;

[0015] a third single-polarization lateral port extending along a third axis transverse to the main direction;

[0016] a fourth single-polarization lateral port opposite the third lateral port and extending along a fourth axis transverse to the main direction;

[0017] said first, second, third and fourth transverse axes each forming an angle with the main direction of between 15° and 75°,

[0018] the six-port orthomode transducer being characterized by a high-pass filter disposed between the side ports and the output port, said high-pass filter comprising at least two filtering slots.

[0019] The orthomode transducer can 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.

[0020] The platform may comprise at least one support arch extending radially from the main direction.

[0021] 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°.

[0022] The orthomode transducer can be characterized in that a smaller dimension of each of the four side ports is parallel to the main direction.

[0023] The outlet port may comprise at least one groove disposed on an inner wall of the outlet port.

[0024] The platform may include a protruding impedance matching element that may extend in the main direction.

[0025] A diameter of the inlet port may be greater than a diameter of the outlet port.

[0026] The orthomode transducer can be characterized by a double symmetry along two planes orthogonal to each other, each of the two orthogonal planes comprising the main direction.

[0027] 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.

[0028] Each of the four low-pass filters may comprise at least one internal face provided with slots.

[0029] 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

[0030] Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which:

[0031] [Fig-1] illustrates a three-quarter view of a six-port orthomode transducer.

[0032] [Fig.2] illustrates a longitudinal section of a six-port orthomode transducer.

[0033] [Fig.3] illustrates a longitudinal section of a six-port orthomode transducer.

[0034] [Fig.4] illustrates a top view of a six-port orthomode transducer including a filtering platform.

[0035] [Fig.5a] illustrates a filtering platform suitable for additive manufacturing.

[0036] [Fig.5b] illustrates a top view of a filtering platform suitable for the fa additive building.

[0037] [Fig.6] illustrates a longitudinal section of a filtering platform suitable for the additive manufacturing.

[0038] [Fig.7] illustrates a side section of a dual polarization diplexer comprising a six-port orthomode transducer and notched side filters on one side.

[0039] [Fig.8] illustrates a side section of a dual polarization diplexer comprising a six-port orthomode transducer and two-sided notched side filters. Example embodiment(s) of the invention

[0040] [Fig.l] 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.

[0041] During the present description, it will be assumed that the orthomode transducer of the present invention is oriented in the following manner: 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 are in a plane orthogonal to the z direction and correspond to the orthogonal directions of the polarizations.

[0042] The input port 10 consists of a standard waveguide whose section can be circular, rectangular so as to receive / transmit signals with circular, elliptical or linear polarization. In general, the section of the input port can be any geometric shape deemed suitable by those skilled in the art, this including for example pentagonal, hexagonal, polygonal plus six sections sides, but also combinations of polygon sections with curved sides. When used in a dual-polarized 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, in turn, arranged coaxially with the input port 10 and is also dual-polarized. Similarly, the output port 11 is a waveguide whose section can 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.

[0043] 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 PL. 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.

[0044] In an embodiment illustrated in [Fig.l] 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.

[0045] As illustrated in [Fig.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.

[0046] In an embodiment illustrated in [Fig.4], the arrangement of the side ports (12,13,14,15) as well as the sections of the inlet 10 and outlet 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.

[0047] 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 filtering slots 21 making it possible to reject low frequencies so that only high frequencies can pass through the output port 11.

[0048] 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.

[0049] In X band, low frequencies are typically between 7.25GHz and 7.75GHz and high frequencies between 7.9GHz and 8.4GHz.

[0050] 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.

[0051] 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.

[0052] In the QV band, the low frequencies are typically between 37.5 GHz and 42.5 GHz and the high frequencies between 42.5 GHz and 52.5 GHz, or sub-portions of these particular bands.

[0053] In Ku / Ka band, the low frequencies are typically between 10.7GHz and 12.75GHz and the high frequencies between 13.25GHz and 21GHz, or sub-portions of these particular bands; alternatively, or complementary, the low frequencies are typically between 13.25GHz and 21.2GHz and the high frequencies between 13.25GHz and 21.2GHz and the high frequencies between 27GHz and 31GHz or sub-portions of these particular bands.

[0054] 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.

[0055] In one embodiment, the outlet port 11 has a section with a diameter smaller than the diameter of the section of the inlet port 10 so that part of the The input port frequency band corresponds to the region below the output port cutoff frequency. This reduction in diameter therefore allows for a "virtual" complementary filtering to that of the high-pass filter.

[0056] 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.

[0057] In a preferred embodiment illustrated in [Fig.2], the high-pass filter comprises a platform 20 in which the filtering slots are arranged. The platform 20 extends radially around the main direction.

[0058] 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 upper surface of the platform is perpendicular to the main direction 100.

[0059] 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.

[0060] In the embodiment illustrated in [Fig.4], four triangular filtering slots 21 are formed by the platform 20 on the one hand and the internal walls 110 of the outlet port 11. The platform comprises four arms extending from the main direction 100 towards the internal walls 110 of the outlet port 11.

[0061] 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 joining at the center of the platform at the main direction.

[0062] 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 axis (z) advantageously between 15° and 75°, preferably between 35° and 55°. [Fig. 6] illustrates a sectional view of the platform in which two support arches 22 form an angle [3 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.

[0063] In one embodiment, grooves 23 parallel to the main direction can be arranged on the internal 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.

[0064] As illustrated in [Fig.5b], the platform 20 can 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 internal wall (not shown in [Fig.5b]) of the output port being provided with a groove 23.

[0065] The platform 20 may also comprise a projecting impedance matching element 24. As illustrated in [Fig.5a], this projecting element may extend in the main direction 100 from the platform 20, the platform thus being able to serve as a support for the projecting element during additive manufacturing.

[0066] 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 10. Such an antenna also generally comprises low-pass filters 30 connected to the side ports (12, 13, 14, 15).

[0067] [Fig.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.

[0068] [Fig.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.

[0069] 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 polarization 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.

[0070] Reference numbers used in the figures [Tables 1] 1 Orthomode Transducer 10 Input Port 100 Main Direction 11 Output Port 110 Output Port Inner Wall 12 First Side Port 13 Second Side Port 14 Third Side Port 15 Fourth Side Port 120 First Transverse Axis 130 Second Transverse Axis 140 Third Transverse Axis 150 Fourth Transverse Axis 20 Platform 21 Filter Slot 22 Support Arch 220 Cantilever Face 23 Ridge 24 Impedance Matching Salient 30 Low-Pass Filter

Claims

Claims

1. A six-port orthomode transducer (1) made by additive manufacturing, and comprising a dual-polarized input port (10); a dual-polarized 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-polarized lateral port (12) extending along a first axis transverse (120) to the main direction (100); a second single-polarized 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-polarized 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 (20).

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 (|3) 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 smallest dimension of each of the four side 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 4, or 2 and 5, or 2 and 6, the platform (20) comprising a projecting impedance matching element (24).

8. An 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. An antenna according to claim 10, each of the four low-pass filters (30) comprising at least one internal face provided with slots.

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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