Six-port orthogonal mode junction

Abstract

The invention relates to a six-port quadrature mode converter (1) produced by additive manufacturing and comprising: a dual polarized input port (10); a dual polarization output port (11); the input port and the output port define a main direction (100) corresponding to a signal propagation direction 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); the first, second, third and fourth lateral axes each form an angle comprised between 15 DEG and 75 DEG with the main direction (100), the six-port quadrature mode converter being characterized by a high-pass filter arranged between the side port and the output port, the high-pass filter comprising at least two filter slots (21). The invention also relates to a transceiver antenna comprising such an orthogonal mode converter and a plurality of low-pass filters.

Description

Technical Field

[0001] The present invention relates to a six-port orthogonal mode converter suitable for additive manufacturing. Background Art

[0002] In the field of radio frequency transmission, a dual-polarized antenna is an antenna capable of transmitting and receiving electromagnetic waves according to two orthogonal polarizations. These antennas usually include a radiating element (usually of the horn type) and a feed chain. The feed chain must specifically allow the two orthogonal polarizations to be distinguished so as to be able to combine the two signals (in transmission) and separate the two signals in reception, respectively. This distinction can be achieved with the help of a dual-polarized orthogonal mode converter (OMT), such as a "turnstile" junction, which has an input port connected to the horn and two pairs of side ports placed opposite each other, each pair of ports allowing one of the polarizations to be isolated.

[0003] When such an antenna is also dual-band, ie, can operate in two frequency ranges, the feed chain must also be able to discriminate between the various frequency ranges. This discrimination is usually achieved by means of a bandpass filter arranged in the feed chain.

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

[0005] However, the recent boom in additive manufacturing in the field of radio frequency transmission has led to an increased demand to improve the design of such antennas so that they can be produced by additive manufacturing. In particular, dual-polarized antennas and orthogonal mode converters usually have relatively large cantilever sections, such as lateral waveguides or certain parts of bandpass filters, making efficient and inexpensive additive manufacturing impossible. This is because the overhanging area needs to be supported during manufacturing, and the support must then be removed manually, resulting in a loss of both time and cost.

[0006] Document US2013 / 0342282A1 describes a six-port orthogonal mode converter, in which two pairs of rectangular cross-section side ports make it possible to distinguish two orthogonal polarizations of the wave propagating in the main waveguide. The four side ports extend radially with respect to the main propagation direction of the signal in the main waveguide, i.e. perpendicular to the main propagation direction. A low-pass filter is connected to one port of the orthogonal mode converter, with its direction 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 and the low-pass filters are not suitable for additive manufacturing for the reasons mentioned above.

[0007] The document "3D Printing of a Monolithic K / Ka-Band Dual-Circular Polarization Antenna-Feeding Network" by G. Addamo et al., published in IEEE Access, Vol. 9, pp. 88243-88255, 2021, describes a six-port orthogonal mode converter suitable for additive manufacturing. Frequency discrimination is achieved on the one hand by a virtual filter consisting of a main waveguide with a gradually narrowing inner diameter, and on the other hand by a low-pass filter connected to the side port. The side ports are oriented so that two pairs of side ports form an H-plane divider with the input port, i.e., the port intended to be connected to the antenna horn. In other words, the longest side of the side port opening is aligned with the propagation direction. Summary of the invention

[0008] It is an object of the present invention to provide a six-port quadrature mode converter which is not subject to the limitations of those known in the prior art.

[0009] Another object of the present invention is to provide a six-port orthogonal mode converter suitable for additive manufacturing.

[0010] Another object of the invention is to propose a six-port orthogonal mode converter capable of discriminating between two frequency bands.

[0011] According to the invention, these objects are achieved in particular by means of a six-port orthogonal mode converter produced by additive manufacturing and comprising:

[0012] Dual polarization input port;

[0013] Dual polarization output port;

[0014] The input port and the output port define a main direction corresponding to a direction of propagation of a signal between the input port and the output port;

[0015] a first single polarization side port extending along a first axis transverse to the main direction;

[0016] a second single polarization side port, the second single polarization side port facing the first side port and extending along a second axis transverse to the main direction;

[0017] a third single-polarization side port, the third single-polarization side port extending along a third axis transverse to the main direction;

[0018] a fourth single-polarization side port, the fourth single-polarization side port facing the third side port and extending along a fourth axis transverse to the main direction;

[0019] The first, second, third and fourth transverse axes each form an angle comprised between 15° and 75° with the main direction,

[0020] The six-port orthogonal mode converter is characterized by a high-pass filter arranged between the side port and the output port, wherein the high-pass filter comprises at least two filter slots.

[0021] The orthogonal mode converter may be characterized in that the high-pass filter comprises a platform extending radially with respect to the main direction, at least two filter slots being arranged on the platform.

[0022] The platform may comprise at least one supporting arch extending radially with respect to the main direction.

[0023] In order to facilitate additive manufacturing thereof, at least one supporting arch may have at least one cantilevered surface which forms an angle of between 15° and 75° with the main direction.

[0024] The orthogonal mode converter may be characterized in that the minor dimension of each of the four side ports is parallel to the main direction.

[0025] The output port may include at least one ridge disposed on an inner wall of the output port.

[0026] The platform may include a protruding impedance matching element extending along the main direction.

[0027] The diameter of the input port may be larger than the diameter of the output port.

[0028] The orthogonal mode converter may be characterized by a dual symmetry along two mutually orthogonal planes, each of the two orthogonal planes including a main direction.

[0029] The above object is also achieved by an antenna for transmitting and / or receiving dual-polarized signals, the antenna comprising an orthogonal mode converter as described above and comprising four low-pass filters, each side port being connected to one of the four low-pass filters.

[0030] Each of the four low-pass filters may include at least one inner face provided with a notch.

[0031] The antenna may be characterized by a dual symmetry along two mutually orthogonal planes, each of the two orthogonal planes including a main direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] An implementation example of the invention is indicated in the description shown in the accompanying drawings, in which:

[0033] Figure 1 A three-quarter view of a six-port orthogonal mode converter is shown.

[0034] Figure 2 A longitudinal cross section of a six-port orthogonal mode converter is shown.

[0035] Figure 3 A longitudinal cross section of a six-port orthogonal mode converter is shown.

[0036] Figure 4 A top view of a six-port orthogonal mode converter including a filtering platform is shown.

[0037] Figure 5a Illustration of a filtering platform suitable for additive manufacturing.

[0038] Figure 5b A top view of a filtering platform suitable for additive manufacturing is shown.

[0039] Figure 6 Illustration of a longitudinal cross section of a filtering platform suitable for additive manufacturing.

[0040] Figure 7 A side cross-section of a dual polarization duplexer including a six-port orthogonal mode converter and a side filter notched on one face is shown.

[0041] Figure 8 A side cross-section of a dual-polarization duplexer is shown, the duplexer comprising a six-port orthogonal mode converter and side filters notched on both sides. DETAILED DESCRIPTION

[0042] Figure 1 The orthogonal mode converter 1 according to the present invention is illustrated, comprising an input port 10 and a dual polarized output port 11, thereby determining a main direction 100 corresponding to the signal propagation direction between the input port and the output port. Four side ports (12, 13, 14, 15) are connected to the orthogonal mode converter along four axes transverse to the main direction.

[0043] In the present description, it will be assumed that the orthogonal mode converter of the present invention is oriented as follows: the main propagation direction between the input port 10 and the output port corresponds to the z direction coinciding with the 3D printing direction. The x and y directions lie in a plane orthogonal to the z direction and correspond to orthogonal directions of polarization.

[0044] The input port 10 comprises a standard waveguide, the cross section of which may be circular, rectangular, so as to receive / transmit signals with circular polarization, elliptical polarization or linear polarization. Generally, the cross section of the input port may be any geometric shape deemed suitable by a person skilled in the art, including, for example, a pentagon, a hexagon, a polygonal cross section with more than six sides, and a combination of a polygonal cross section with curved sides. In the use of a dual-polarized antenna, the input port 10 is usually connected to a waveguide or directly to a radiating element such as a horn. The output port 11 is itself arranged coaxially with the input port 10 and is also dual-polarized. Similarly, the output port 11 is a waveguide, the cross section of which may be any geometric shape deemed suitable by a person skilled in the art, including, for example, a pentagon, a hexagon, a polygonal cross section with more than six sides, and a combination of a polygonal cross section with curved sides.

[0045] Between the input port 10 and the output port 11, the first side port 12 extends along a first axis 120 transverse to the main direction 100 and faces the second side port 13, which extends along a second axis 130 also transverse to the main direction 100. The first port and the second port allow signals to be separated / combined according to a first polarization P1. The third side port 14 extends along a third axis 140 transverse to the main direction 100 and faces the fourth side port 15, which extends along a fourth axis 150 transverse to the main direction 100. The third port and the fourth port allow signals to be separated / combined according to a second polarization P2. Therefore, each of the four side ports is single-polarized.

[0046] exist Figure 1 In the embodiment shown, the side ports (12, 13, 14, 15) have a rectangular cross section, wherein the smallest side of the rectangular cross section is aligned with the main direction 100, so that the combination of the input port 10 and a pair of opposite side ports (i.e. corresponding to the same polarization) forms an E-plane splitter / combiner. Therefore, the electric field directions of the waves propagating in the two side ports corresponding to the same polarization are opposite.

[0047] like Figure 3As shown, each of the first, second, third and fourth axes (120, 130, 140, 150) forms an angle with the main direction 100 comprised between 15° and 75°, preferably between 35° and 55°. This inclination relative to the z-direction enables additive manufacturing of the side ports. In fact, the z-axis generally coincides with the 3D printing direction, so the inclination of the side ports relative to this direction helps to reduce the physical constraints imposed by gravity on these side ports, and therefore helps to reduce or even eliminate the need for supports during manufacturing. The inclination of the side ports can also make it possible to improve the compactness of the orthogonal mode converter by limiting its external volume.

[0048] exist Figure 4 In the illustrated embodiment, the arrangement of the side ports (12, 13, 14, 15) and the cross-sections of the input port 10 and the output port 11 enable the entire orthogonal mode converter 1 according to the present invention to have dual-plane symmetry along two mutually orthogonal planes, one of the two planes of symmetry including the first and second axes (120, 130) and the main direction 100, and the other of the two planes of symmetry including the third and fourth axes (140, 150) and the main direction 100.

[0049] The orthogonal mode converter 1 of the present invention is provided with a high pass filter, which is arranged between the side port and the output port 11. The high pass filter includes at least two filter slots 21 for filtering low frequencies so that only high frequencies can pass through the output port 11.

[0050] In the context of the present invention, the terms "high frequency" and "low frequency" may correspond to different value ranges according to embodiments of the present invention. In fact, the present invention may be implemented in different devices intended for various frequency bands, depending on its application. By way of example, the present invention may generally be used in devices intended for X, Ku, Ka, QV, Ku / Ka and / or Ka / QV bands.

[0051] In the X-band, the low frequencies are generally included between 7.25 GHz and 7.75 GHz, while the high frequencies are included between 7.9 GHz and 8.4 GHz.

[0052] In the Ku-band, the lower frequencies are generally included between 10.7 GHz and 12.75 GHz, while the higher frequencies are included between 13.25 GHz and 4.5 GHz, or sub-portions of these specific bands.

[0053] In the Ka-band, the lower frequencies are generally included between 17.3 GHz and 21.2 GHz, while the higher frequencies are included between 27 GHz and 31 GHz, or sub-portions of these specific bands.

[0054] In the QV band, the lower frequencies are generally included between 37.5 GHz and 42.5 GHz, while the higher frequencies are included between 42.5 GHz and 52.5 GHz, or sub-portions of these specific bands.

[0055] In the Ku / Ka band, the low frequencies are typically included between 10.7 GHz and 12.75 GHz, and the high frequencies are included between 13.25 GHz and 21 GHz, or sub-portions of these specific bands; alternatively or complementarily, the low frequencies are typically included between 13.25 GHz and 21.2 GHz, and the high frequencies are included between 13.25 GHz and 21.2 GHz, and the high frequencies are included between 27 GHz and 31 GHz, or sub-portions of these specific bands.

[0056] In the Ka / QV band, the lower frequencies are generally included between 27 GHz and 42.5 GHz, while the higher frequencies are included between 42.5 GHz and 52.5 GHz, or sub-portions of these specific bands.

[0057] In one embodiment, the cross section of the output port 11 has a smaller diameter than 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. Thus, this reduction in diameter allows additional "virtual" filtering to the high-pass filter.

[0058] As for low frequencies, they propagate in the side ports (12, 13, 14, 15), which themselves can be connected to low-pass filters in order to filter out high frequencies.

[0059] In a preferred embodiment, the high pass filter comprises a platform 20 in which a filter slot 21 is arranged. The platform 20 extends radially around the main direction. Figure 3 , and comprises an upper surface facing the input port 10 and a lower surface facing the output port 11. Preferably, the upper surface of the platform is perpendicular to the main direction 100.

[0060] The filter slot 21 may be formed on the one hand by the platform 20 and on the other hand by the inner wall of the output port 11. Alternatively or additionally, the filter slot 21 may be formed completely by the platform 20, ie each side of the slot is formed by a section of the platform.

[0061] exist Figure 4 In the embodiment shown, four triangular filter slots 21 are formed on the one hand by the platform 20 and the inner wall 110 of the output port 11. The platform comprises four arms extending from the main direction 100 towards the inner wall 110 of the output port 11.

[0062] The platform 20 may include at least one support arch 22 to enhance the stability of the platform during additive manufacturing and / or during use of an orthogonal mode converter. Figure 5a As shown, the platform 20 may include a plurality of supporting arches 22 that meet at the center of the platform in a main direction.

[0063] To facilitate additive manufacturing of the platform 20 and the supporting arch 22 , the supporting arch forms an angle REF with respect to the cantilever face 220 in the z direction with the axis (z), advantageously comprised between 15° and 75°, preferably between 35° and 55°. Figure 6 A cross-sectional view of the platform is shown, wherein the two supporting arches 220 form an angle β with the main direction 100. As with the side ports, the optimum inclination for additive manufacturing is about 45°. However, for reasons related, for example, to the internal geometry of the orthogonal mode converter, an inclination of the cantilever face comprised between 15° and 75° may also be relevant.

[0064] In one embodiment, ridges 23 parallel to the main direction may be provided on the inner surface of the output port 11. These ridges make it possible, for example, to increase the width of the frequency band and / or adjust the impedance of the output port 11. Figure 4 As shown, the connection groove of the high-pass filter can divide the output port into multiple waveguides, and a ridge 23 can be provided on the inner wall of the output port. The platform 20 can, for example, divide the output port 11 into four waveguides with triangular cross-sections, and one side of each cross-section corresponds to a side determined by the inner wall 110 of the output port provided with the ridge 23.

[0065] The platform 20 may also include a protruding impedance matching element 24. Figure 5a As shown, the protruding element may extend from the platform 20 in a main direction 100 , so that the platform can serve as a support for the protruding element during additive manufacturing.

[0066] The orthogonal mode converter 1 is typically used in a feed chain of a radio frequency antenna, which also includes an antenna horn connected to an input port 11. Such an antenna typically also includes a low pass filter 30 connected to a side port (12, 13, 14, 15).

[0067] Figure 7An embodiment is illustrated in cross-section, wherein each side port is connected to a low-pass filter 30, for example a low-pass filter with a sawtooth shape on one side wall. Each of the low-pass filters extends along the main direction 100. The filter is advantageously symmetrical along the two symmetry planes mentioned above, i.e. along a plane including the main direction 100 and the first and second transverse axes (120, 130) and along another plane including the main direction 100 and the third and fourth transverse axes (140, 150). Thus, the orthogonal mode converter and low-pass filter assembly maintains a dual-plane symmetry.

[0068] Figure 8 An embodiment is shown in which the low pass filters 30 connected to the side ports have two serrated inner walls. These filters 30 also extend along the main direction 100. Likewise, a double symmetry of the orthogonal mode converter and low pass filter components can be achieved.

[0069] In a feed chain comprising an orthogonal mode converter according to the invention and a low-pass filter as described above, the two pairs of low-pass filters corresponding to the first polarization and the 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 orthogonal mode converter. Advantageously, the single-band combiner and the single-band orthogonal mode converter are also arranged to maintain the dual symmetry of the feed chain.

[0070] Reference numerals used in the drawings

[0071] 1Quadrature Mode Converter

[0072] 10 Input ports

[0073] 100 main directions

[0074] 11 output ports

[0075] 110 Inner wall of output port

[0076] 12 First side port

[0077] 13 Second side port

[0078] 14 Third side port

[0079] 15Fourth side port

[0080] 120 first transverse axis

[0081] 130 second transverse axis

[0082] 140 Third transverse axis

[0083] 150 Fourth transverse axis

[0084] 20 Platforms

[0085] 21 filter slots

[0086] 22 Support arch

[0087] 220 cantilever surface

[0088] 23 Ridge

[0089] 24 Highlight impedance matching components

[0090] 30 Low pass filter

Claims

1. A six-port orthogonal mode converter (1), the six-port orthogonal mode converter (1) being produced by additive manufacturing and comprising: Dual polarization input port (10); Dual polarization output port (11); The input port and the output port define a main direction (100) corresponding to a propagation direction of a signal between the input port (10) and the output port (11); A first single-polarization side port (12), the 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), the 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), the 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), the fourth single-polarization side port (15) being opposite to the third side port (14) and extending along a fourth axis (150) transverse to the main direction (100); The first transverse axis, the second transverse axis, the third transverse axis and the fourth transverse axis each form an angle with the main direction (100) comprised between 15° and 75°, The six-port orthogonal mode converter is characterized by a high-pass filter arranged between the side port and the output port, the high-pass filter comprising at least two filter slots (21).

2. The orthogonal mode converter (1) according to claim 1, characterized in that: The high-pass filter comprises a platform (20) extending radially relative to the main direction (100), and the at least two filter slots (21) are arranged on the platform.

3. The orthogonal mode converter (1) according to claim 2, the platform (20) comprising at least one supporting arch (22) extending radially with respect to the main direction (100).

4. The orthogonal mode converter (1) according to claim 3, wherein the at least one supporting arch (22) has at least one cantilever surface (220), and the at least one cantilever surface (220) forms an angle (β) comprised between 15° and 75° with the main direction (100).

5. The orthogonal mode converter (1) according to one of the preceding claims, characterized in that The minor dimension of each of the four side ports (12, 13, 14, 15) is parallel to the main direction (100).

6. The orthogonal mode converter (1) according to one of the preceding claims, the output port (11) comprising at least one ridge (23) arranged on an inner wall (110) of the output port.

7. An orthogonal mode converter (1) according to one of claims 2 to 6 when dependent on claim 2, the platform (20) comprising a protruding impedance matching element (24).

8. The orthogonal mode converter (1) according to one of the preceding claims, the diameter of the input port (10) being larger than the diameter of the output port (11).

9. The orthogonal mode converter (1) according to one of the preceding claims, characterized in that There is a double symmetry along two mutually orthogonal planes, each of the two orthogonal planes including the main direction (100).

10. An antenna for transmitting and / or receiving dual-polarized signals, the antenna comprising an orthogonal mode converter (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. The antenna according to claim 10, each of the four low-pass filters (30) comprising at least one inner face provided with a notch.

12. Antenna according to one of claims 10 to 11, characterized in that There is a double symmetry along two mutually orthogonal planes, each of the two orthogonal planes including the main direction (100).

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