Compact dual-band orthomode transducer with linear polarization

Abstract

The present invention relates to a wideband, linearly polarized orthomode transducer obtained by additive manufacturing, comprising: a hybrid coupler comprising: a first waveguide comprising a first input port and a first output port with single polarization; and a second waveguide comprising a second input port and a second output port with single polarization; and a coupling portion connecting the first waveguide to the second waveguide; a septum polarizer comprising: a third input port with single polarization connected to the first output port; and a fourth input port with single polarization connected to the second output port; and a third output port with single polarization; wherein the first and second waveguides are arranged symmetrically with respect to a plane of symmetry containing a septum of the septum polarizer. Figure to be published with the abstract: Figure 4a

Description

Title of the invention: Compact dual-band orthomode transducer with linear polarization technical field

[0001] The present invention relates to a linearly polarized orthomode transducer that is both compact and dual-band. State of the art

[0002] Orthomode transducers (abbreviated TOM) are passive components widely used in radio frequency antennas to enable both receiving and transmitting.

[0003] As their use is particularly widespread in antennas onboard telecommunications satellites, limiting the weight and size of such antennas is a crucial issue. Furthermore, the ability of an antenna (and therefore of a TOM) to transmit / receive on several frequency bands is also a determining factor.

[0004] However, traditional TOMs generally struggle to be compact while guaranteeing a wide transmit / receive bandwidth. Indeed, on the one hand, there are TOMs, such as side-arm TOMs, that are compact but not wide-band. In some cases, a side arm can be extended to operate in a second frequency band; however, this extension is only possible for one of the two polarizations. On the other hand, there are TOMs, such as Boifot junctions or Turnstile junctions, that are wide-band but not compact since they have an aperture larger than the wavelength X of a wave having the highest operating frequency of the TOM.

[0005] Document EP2330681 Al describes a single-band orthomode transducer comprising a septum polarizer whose septum allows a phase shift of 180° so as to produce a 45° polarization.

[0006] US patent 2012 / 0319799Al describes an orthomode transducer comprising a first septum polarizer connected to a second corrugated polarizer, which undoes the circular polarization generated by the first polarizer and produces a 45° polarization. A wider bandwidth is theoretically possible if the length of the transducer is increased, which increases its size.

[0007] Document EP2047564B1 describes an orthomode transducer comprising a coupling portion in the form of a side arm coupled to the transducer via a slot, allowing a 90° rotation of the side waveguide. The side arm increases the transducer's footprint. Furthermore, the broadband performance is not demonstrated for this type of transducer. Brief summary of the invention

[0008] An object of the present invention is to propose an orthomode transducer free from the limitations of known orthomode transducers.

[0009] Another object of the invention is to provide a broadband orthomode transducer with a reduced size.

[0010] These objectives are achieved by means of the subject matter of the claims and in particular by means of a wideband, linearly polarized orthomode transducer obtained by additive manufacturing comprising:

[0011] a hybrid coupler comprising:

[0012] a first waveguide comprising a first input port and a first single-polarized output port; and

[0013] a second waveguide, comprising a second input port and a second single-polarization output port; and

[0014] a coupling portion connecting the first waveguide to the second waveguide;

[0015] the orthomode transducer further comprising:

[0016] a septum polarizer comprising:

[0017] a third single-polarization input port connected to the first output port; and

[0018] a fourth single-polarization input port connected to the second output port; and

[0019] a third single-polarization output port;

[0020] wherein the first and second waveguides are arranged symmetrically with respect to a plane of symmetry containing a septum of the septum polarizer.

[0021] The symmetrical arrangement of the first and second waveguides of the coupler makes it possible to limit the transducer's footprint, i.e., to obtain a compact cross-section along the entire length of the transducer. This results in a reduced size, allowing, for example, the densification of such devices in an antenna array.

[0022] According to a first embodiment, the coupling portion connects a first lateral face of the first waveguide and a second lateral face of the second waveguide, the first and second lateral faces being arranged in the same plane.

[0023] The first lateral face can correspond to a face of the first waveguide of minimum dimension, and the second lateral face corresponds to a face of the second waveguide of minimum dimension.

[0024] Advantageously, this configuration allows for a further reduction in size by arranging the two waveguides of the coupler so that their largest lateral faces are opposite each other. Thus, the coupler's footprint is reduced.

[0025] According to one embodiment, the coupling portion comprises a prism with a trapezoidal base, a first portion of a rectangular face of the prism being in contact with the first lateral face of the first waveguide and a second portion of the rectangular face of the prism being in contact with the second lateral face of the second waveguide.

[0026] This geometry of the coupling portion makes it easier to manufacture the additive manufacturing of the coupler by limiting the cantilevered portions.

[0027] The coupling portion may include an impedance matching element.

[0028] According to a second embodiment, the coupling portion connects a first lateral face of the first waveguide and a second lateral face of the second waveguide, the first and second lateral faces being arranged in distinct and parallel planes.

[0029] This arrangement advantageously limits the transducer's footprint by placing the coupling portion between the two waveguides. Indeed, the external faces of the coupler, that is, the faces of one waveguide not directly facing a face of the other waveguide, do not include any protruding elements that would increase the transducer's footprint.

[0030] Advantageously, the coupling portion can comprise a plurality of branches, a first end of each branch being connected to the first waveguide and a second end of each branch being connected to the second waveguide.

[0031] According to one embodiment, each branch forms a gable roof, the first gable of the roof being adjacent to the first lateral face and the second gable of the roof being adjacent to the second lateral face. This geometry of the branches facilitates additive manufacturing by limiting the cantilevered portions.

[0032] A roof edge formed by the junction of the first and second slopes can be contained in a plane perpendicular to a printing direction.

[0033] In order to facilitate additive manufacturing, the first panel can form an angle with the first lateral face of the first waveguide of between 35° and 55° and the second panel can form an angle with the second lateral face of the second waveguide of between 35° and 55°.

[0034] In order to further limit the sections of the cantilevered coupling portion, each branch can form a double gable roof comprising a first gable roof of which a first gable is adjacent to the first lateral face and a second gable is adjacent to the second lateral face, and comprising a second gable roof, of which a third gable is adjacent to the first lateral face and a fourth gable is adjacent to the second lateral face.

[0035] The first and third panels can advantageously form an angle with the first lateral face of between 35° and 55°, and the second and fourth panels can form an angle with the second lateral face between 35° and 55°.

[0036] An edge of the first roof formed by the junction of the first and second panels can form an angle with a printing direction of between 35° and 55° and an edge of the second roof formed by the junction of the third and fourth panels can form an angle with the printing direction of between 35° and 55°. Brief description of the figures

[0037] Examples of implementation of the invention are given in the description illustrated by the accompanying figures in which:

[0038] [Fig-1] schematically illustrates an orthomode transducer according to the invention.

[0039] [Fig.2] illustrates a septum polarizer.

[0040] [Fig.3] illustrates a hybrid coupler comprising a trapezoidal coupling portion.

[0041] [Fig.4a] and [Fig.4b] illustrate an orthomode transducer comprising the coupler hybrid of the [Fig.3].

[0042] [Fig.5a] and [Fig.5b] illustrate a hybrid coupler whose coupling portion comprises a plurality of branches adapted for additive manufacturing.

[0043] [Fig.6a] and [Fig.6b] illustrate a hybrid coupler whose coupling portion comprises a plurality of branches adapted for additive manufacturing.

[0044] [Fig.7a] and [Fig.7b] illustrate an orthomode transducer comprising the coupler hybrid illustrated in figures 6a and 6b. Example(s) of an embodiment of the invention

[0045] As illustrated in [Fig.1], the orthomode transducer of the present invention comprises a hybrid coupler 1 connected to a septum polarizer 2. The hybrid coupler 1 comprises two waveguides (10,11) arranged in parallel and connected to each other by a coupling portion 12. The septum polarizer 2 is connected to the output ports of the hybrid coupler 1 via two input ports.

[0046] When a radio frequency device including this orthomode transducer is operating in transmit mode, an electromagnetic wave is propagated from the hybrid coupler 1 to the septum polarizer 2, and when it is operating in receive mode, from the septum polarizer to the hybrid coupler. The terminology used in the context of the present invention, such as "input port" or "output port," refers to a transmit mode of operation, although the transducer can operate interchangeably in transmit and / or receive mode.

[0047] The direction of wave propagation in the transducer is therefore parallel to the longitudinal direction of the waveguides of the coupler 1 and the polarizer 2.

[0048] The orthomode transducer of the present invention is obtained by additive manufacturing. The term "additive manufacturing" describes any manufacturing process of Parts are created by adding material, according to computer data stored on a computer medium and defining a model of the part. In addition to stereolithography, the term also refers to other manufacturing methods by hardening or coagulation of liquid or powder, including but not limited to methods based on inkjets (binder jetting), DED (Direct Energy Deposition), EBFF (Electron beam freeform fabrication), FDM (fused deposition modeling), PFF (plastic freeforming), aerosols, BPM (ballistic particle manufacturing), powder bed fusion, SLS (Selective Laser Sintering), ALM (Additive Layer Manufacturing), polyjet, EBM (electron beam melting), photopolymerization, etc.

[0049] Thus, although the orthomode transducer comprises two elements with different functions, i.e. a hybrid coupler and a septum polarizer, its manufacture requires no assembly after the 3D printing steps. The coupler and the polarizer are therefore typically made as a single unit.

[0050] Hybrid couplers are four-port directional couplers used to separate or combine waves with specific phase relationships. There are primarily two types of hybrid couplers: one producing a 90° phase shift between the two output ports and the other producing a 180° phase shift between the two output ports. Hybrid couplers also function as power dividers since the wave typically undergoes a 3 dB attenuation; that is, the waves propagated by each of the output ports have a power equal to 50% of the power of the input wave.

[0051] Fig. 2 illustrates a prior art hybrid coupler of Riblet type consisting of two waveguides coupled together via an opening in the contiguous walls of the two waveguides.

[0052] As schematically illustrated in [Fig.1], the first waveguide 10 thus comprises a first input port 100 and a first output port 101, and the second waveguide comprises a second input port 110 and a second output port 111. The phase shift at the output ports depends on the coupling portion 12. Each of these four ports is single-polarized.

[0053] The coupling portion 12 of the coupler 1 allows a wave propagating in the first waveguide 10 to pass, at least partially, into the second waveguide 11 and a wave propagating in the second waveguide 11 to pass, at least partially, into the first waveguide 10.

[0054] Thus, by way of example, a wave propagating through the first input port 100 of the first waveguide 10 will be distributed between the first and second waveguides 10,11 via the coupling portion 12 and thus exit the hybrid coupler 1 through the first and second output ports 100,101.

[0055] The output ports 101, 111 of the hybrid coupler are connected to the polarizer at The polarizer is connected to the septum 2 via a third input port 200 and a fourth input port 210, respectively. The other end of the polarizer includes a third output port 201. The third output port can be connected to a radiating element of the antenna, or even function as a radiating element itself in some embodiments. The third and fourth input ports 200 and 210 of the polarizer are single-polarized. The third output port 201 of the polarizer is dual-polarized.

[0056] Although the various embodiments shown in the figures illustrate waveguides with rectangular cross-sections, the invention is not limited to these geometries. Indeed, the first and second waveguides 10, 11 as well as the septum polarizer 2 can also have a circular, elliptical, polygonal (regular or irregular), e.g. triangular, pentagonal, hexagonal, octagonal, etc. cross-section.

[0057] The hybrid coupler 1 is used to excite the third and fourth input ports of the polarizer 2 simultaneously so as to create two circular polarizations. The combination of these two circular polarizations by the septum of the polarizer results in a linear polarization in the third output port 201.

[0058] The septum 22 of the polarizer 2 is arranged in a plane parallel to the direction of wave propagation in the transducer. The septum is typically of variable height, with the highest portion of the septum located at the end of the polarizer comprising the third and fourth input ports 200, 210. The height of the septum can typically decrease linearly or in steps. Figure 2 illustrates a polarizer 2 comprising a septum 22 that decreases in a stepped fashion.

[0059] The orthomode transducer of the present invention can be implemented in various radio frequency devices intended for different frequency bands depending on their application. The present invention can typically be implemented in devices intended for the following bands: X, Ku, Ka, QV, Ku / Ka, Ka / QV.

[0060] Advantageously, the first and second waveguides 10,11 of the hybrid coupler 1 are arranged symmetrically with respect to a plane of symmetry containing the septum 22 of the polarizer 2.

[0061] Advantageously, the cross-sectional area of ​​the septum polarizer 2 measured perpendicular to the direction of wave propagation in the orthomode transducer is the same as the cross-sectional area of ​​the hybrid coupler 1 measured perpendicular to the same direction of propagation. Thus, the diameter of the orthomode transducer (or transducer footprint) measured in a plane perpendicular to the direction of propagation is essentially constant along the direction of propagation. This characteristic makes it possible to increase the compactness of the transducer and therefore reduce its size, particularly for use in a compact antenna array.

[0062] As mentioned above, according to the coupling portion 12, the hybrid coupler 1 This produces a phase shift of 90° or 180°. In transmission, this means that an electromagnetic wave propagating through the first or second input port 100,110 of the hybrid coupler will be split into two waves phase-shifted by 90° or 180° between the first and second output ports 101,111. Each of the two output waves is further attenuated by -3dB relative to the input ground. In reception, the hybrid coupler receives two waves phase-shifted by 90° or 180° and combines them into a single wave whose power is doubled, i.e., increased by 3dB. Two main embodiments are described below, each corresponding to one of the two phase shifts.

[0063] A hybrid coupler 1 according to a first embodiment is illustrated in [Fig.3]. The first and second waveguides 10,11 are connected by the coupling portion 12.

[0064] In transmission, this coupler divides a wave propagated by the first or second input port 100,110 into two waves 90° out of phase via the coupling portion 12. The two input ports of the septum polarizer 2 are thus each simultaneously excited by one of these two waves 90° out of phase, creating two circular polarizations 90° out of phase.

[0065] The two circular polarizations are then combined in the septum polarizer 2, creating in the output port 201 of the septum polarizer, a linearly polarized wave inclined at 45° to the input wave of the hybrid coupler 1.

[0066] According to this first embodiment, the first and second waveguides 10, 11 of the hybrid coupler 1 may have a rectangular cross-section and are arranged parallel to each other, as illustrated in [Fig. 3]. Advantageously, one of the long sides of the rectangular cross-section of the first waveguide is parallel to one of the long sides of the rectangular cross-section of the second waveguide, so that the largest rectangular side walls of the first and second waveguides are arranged in parallel planes.

[0067] The two waveguides 10, 11 are connected by a coupling section 12. More specifically, this coupling section 12 connects one of the small rectangular lateral walls of the first waveguide 10 with one of the small rectangular lateral walls of the second waveguide 11. The two small rectangular walls are arranged in the same plane, this plane being perpendicular to the larger rectangular lateral walls of each waveguide. Each of the smaller walls has an opening in the coupling section so as to allow a wave to pass from the first waveguide to the second or from the second to the first. The coupling section includes a portion of the waveguide extending between these two openings so as to propagate the wave between these two openings.

[0068] In a particular embodiment illustrated in [Fig. 3], the guide portion The waveguide portion of coupling 12 has a trapezoidal geometry. More precisely, this waveguide portion comprises a rectangular base contiguous to the smaller side walls of the first and second waveguides 10,11. The waveguide portion extends in a direction perpendicular to the rectangular base and its cross-section parallel to the base decreases until it forms a rectangular upper face opposite the base, this rectangular face thus having dimensions smaller than those of the base.

[0069] The coupling portion 12 can be provided with one or more impedance matching elements such as grooves, internal protrusions, or openings in a wall of the coupling portion. These elements are intended to optimize signal transmission in the coupling portion. As illustrated in [Fig. 3], an opening on the upper face of the coupling portion can be provided to improve signal transmission between the first and second waveguides 10, 11.

[0070] Figures 4a and 4b illustrate an orthomode transducer according to the first embodiment mentioned above. The hybrid coupler 1 and the septum polarizer 2 are manufactured as a single unit by additive manufacturing, so that no assembly is required to obtain the transducer of the present invention.

[0071] In one embodiment, the layer printing direction for additive manufacturing coincides with the wave propagation direction in the orthomode transducer. In order to reduce, or even eliminate, the need for printing supports during manufacturing, certain portions of the transducer are adapted for additive manufacturing. In particular, certain cantilevered portions are inclined so as to form an angle significantly less than 90° with the printing direction.

[0072] As illustrated in [Fig.3], the coupling portion 12 of the hybrid coupler may include lateral faces forming an angle between 35° and 55° with the propagation direction so as to eliminate the need for possible printing supports.

[0073] According to a second main embodiment, the orthomode transducer includes a hybrid coupler 1 producing a phase shift of 180° between the two waves at the outputs of the coupler when the device is operating in transmission.

[0074] According to this second main embodiment, the coupling portion 12 of the hybrid coupler 1 connects a first lateral face of the first waveguide 10 and a second lateral face of the second waveguide 11, the first and second lateral faces being arranged in distinct and parallel planes.

[0075] In transmission, this hybrid coupler 1 divides a wave propagated by the first or second input port 100, 110 into two waves 180° out of phase via the portion of coupling 12. The two input ports of the septum polarizer 2 are thus each excited simultaneously by one of these two waves out of phase by 180°, thus creating two circular polarizations out of phase by 180°.

[0076] In an embodiment illustrated in Figures 5a and 5b, the coupling portion 12 comprises a plurality of branches 121, each branch being connected on one side to the first lateral face of the first waveguide 10 and on the other side to the second lateral face of the second waveguide 11. Thus, each branch 121 intersects the plane of symmetry of the first and second waveguides 10,11.

[0077] Each branch 121 includes a waveguide enabling the propagation of a wave via an opening in the first waveguide 10 to the second waveguide 11 via an opening in the wall of the second lateral face, or vice versa.

[0078] In an embodiment not shown, each branch 121 comprises a waveguide extending perpendicularly to the lateral faces of the first and second waveguides 10, 11. The cross-section of this waveguide may be triangular, square, rectangular, pentagonal, hexagonal, or more generally polygonal. The cross-section of this waveguide may also include curved portions in addition to or instead of straight portions.

[0079] As before, in order to reduce the use of printing supports, certain portions of the hybrid coupler according to the second main embodiment are inclined with respect to the printing direction. The printing direction is illustrated in Figures 5a and 5b by the z-axis and corresponds to the direction of propagation of a signal in the coupler.

[0080] In particular, the branches 121 may include inclined portions so as to limit the cantilevered sections and thus facilitate, or even make possible, the additive manufacturing of the device.

[0081] In an embodiment illustrated in Figures 5a and 5b, each branch 121 advantageously forms a two-sided roof, each of the sides being adjacent to one or the other of the first and second waveguides 10,11. The edge of the roof formed by the junction of the two sides is typically contained in a plane perpendicular to the printing direction z.

[0082] The inclination of the two sides can be such that the edge of the roof points towards the septum polarizer 2 or towards the first and second inlet ports 100,110. In other words, the two-sided roof has a V-shaped profile pointing in one direction or the other along the printing axis z. Such a geometry of the branches 121 advantageously reduces the cantilevered portions and thus facilitates their additive manufacturing, in particular by eliminating the need for printing supports.

[0083] Each panel forms an angle with the lateral face of the waveguide to which it is adjacent of between 35° and 55°, preferably between 40° and 50°.

[0084] In one embodiment, the branches 121 are symmetrical with respect to the plane of symmetry of the first and second waveguides 10, 11. In other words, each panel is the symmetrical counterpart of the other with respect to the plane of symmetry of the first and second waveguides.

[0085] In an embodiment illustrated in Figures 6a and 6b, each branch 121 advantageously forms a double-pitched roof. More precisely, each branch 121 comprises a first double-pitched roof, each of whose pits is adjacent to the first or second waveguide 10, 11, and a second double-pitched roof, each of whose pits is adjacent to the first or second waveguide 10, 11. The first and second double-pitched roofs are connected to each other such that the edge of the first roof and the edge of the second roof lie in the same plane. The edge of the first roof forms an angle with the edge of the second roof at the point of connection between the two roofs.

[0086] In other words, the embodiment illustrated in Figures 6a and 6b is similar to that illustrated in Figures 5a and 5b, except that each branch of the coupling portion forms a bend in the plane containing the edges of the branches.

[0087] Each of the two edges forms an angle with the printing direction of between 35° and 55°, so that the angle between the two edges is between 70° and 110°.

[0088] In one embodiment, each branch 121 has a double symmetry. Indeed, each branch has a first symmetry with respect to the plane of symmetry of the first and second waveguides 10,11 and a second symmetry with respect to the plane perpendicular to the plane of symmetry of the first and second waveguides containing the printing direction z.

[0089] As illustrated in Figures 7a and 7b, the orthomode transducer comprising the branch coupler has an overall symmetry about a plane containing the septum 22. [Tables 1] Reference numbers used in Figures 1 Hybrid coupler 10 First waveguide 11 Second waveguide 100 First input port 101 First output port 110 Second input port 111 Second output port 12 Coupling portion 121 Branch 122 Pan 123 Edge 2 Septum polarizer 200 Third input port 210 Fourth input port 201 Third output port 22 Septum z Print direction

Claims

Demands

1. A wideband linearly polarized orthomode transducer obtained by additive manufacturing comprising: a hybrid coupler (1) comprising: a first waveguide (10) comprising a first input port (100) and a first output port (101) with single polarization; and a second waveguide (11) comprising a second input port (110) and a second output port (111) with single polarization; and a coupling portion (12) connecting the first waveguide (10) to the second waveguide (11); the orthomode transducer further comprising: a septum polarizer (2) comprising: a third input port (200) with single polarization connected to the first output port (101); and a fourth input port (210) with single polarization connected to the second output port (111); and a third output port (201) with dual polarization;in which the first and second waveguides (10,11) are arranged symmetrically with respect to a plane of symmetry containing a septum (22) of the septum polarizer (2).;

2. Orthomode transducer according to claim 1, wherein the coupling portion (12) connects a first lateral face of the first waveguide (10) and a second lateral face of the second waveguide (11), the first and second lateral faces being arranged in the same plane.

3. Orthomode transducer according to the preceding claim, wherein the first lateral face corresponds to a face of the first waveguide (10) of minimum dimension, and the second lateral face corresponds to a face of the second waveguide (11) of minimum dimension.

4. Orthomode transducer according to the preceding claim, wherein the coupling portion (12) comprises a trapezoidal prism, a first portion of a rectangular face of the prism being in contact with the first lateral face of the first waveguide and a second portion of the rectangular face of the prism being in contact with the second lateral face of the second waveguide.

5. Orthomode transducer according to the preceding claim, the coupling portion (12) comprising an impedance matching element.

6. Orthomode transducer according to claim 1, wherein the coupling portion (12) connects a first lateral face of the first waveguide (10) and a second lateral face of the second waveguide (11), the first and second lateral faces being arranged in distinct and parallel planes.

7. Orthomode transducer according to claim 6, wherein the coupling portion (12) comprises a plurality of branches (121), a first end of each branch being connected to the first waveguide (10) and a second end of each branch being connected to the second waveguide (11).

8. Orthomode transducer according to claim 7, wherein each branch (121) forms a two-sided roof, a first side of the roof being adjacent to the first lateral face and a second side of the roof being adjacent to the second lateral face.

9. Orthomode transducer according to claim 8, wherein a roof edge formed by the junction of the first and second pane is contained in a plane perpendicular to an impression direction (z).

10. Orthomode transducer according to any one of claims 8 or 9, wherein the first pan forms an angle with the first lateral face of the first waveguide of between 35° and 55° and wherein the second pan forms an angle with the second lateral face of the second waveguide of between 35° and 55°.

11. Orthomode transducer according to claim 7, wherein each arm (121) forms a double two-sided roof comprising a first two-sided roof of which a first side is adjacent to the first lateral face and a second side is adjacent to the second lateral face, and comprising a second two-sided roof, of which a third side is adjacent to the first lateral face and a fourth side is adjacent to the second lateral face.

12. Orthomode transducer according to claim 11, wherein the first and third panels form an angle with the first lateral face of between 35° and 55° and wherein the second and fourth panels form an angle with the second lateral face of between 35° and

13. JJ. Orthomode transducer according to any one of claims 11 to 12, wherein an edge of the first roof formed by the junction of the first and second panels forms an angle with an printing direction (z) between 35° and 55° and wherein an edge of the second roof formed by the The junction of the third panel and the fourth panel forms an angle with the printing direction (z) between 35° and 55°.

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