HYBRID COUPLER WITH DIELECTRIC SUBSTRATE AND WAVEGUIDE TRANSITION

Abstract

A hybrid coupler for transmitting equally splitted amplitude and quadrature phase electro-magnetic waves, the hybrid coupler includes a dielectric substrate having a first main surface and a second main surface opposing the first main surface and a stripline placed at the first main surface of the dielectric substrate. The stripline comprising an input port and two output ports. The stripline is formed to provide an equally splitted amplitude and quadrature phase electro-magnetic wave at the output ports based on an input signal received at the input port. The hybrid coupler further includes a rectangular waveguide transition attached to both of the main surfaces of the substrate. The waveguide transition is configured to transmit the equally splitted amplitude and quadrature phase electro-magnetic wave to an antenna.

Claims

1. A hybrid coupler for transmitting equally splitted amplitude and quadrature phase electro-magnetic waves, the hybrid coupler comprising: a dielectric substrate having a first main surface and a second main surface opposing the first main surface; a stripline placed at the first main surface of the dielectric substrate, the stripline comprising an input port and two output ports, wherein the stripline is formed to provide an equally splitted amplitude and quadrature phase electro-magnetic wave at the two output ports based on an input signal received at the input port; and a rectangular waveguide transition attached to both the first main surface and the second main surface of the dielectric substrate, wherein the rectangular waveguide transition is configured to transmit the equally splitted amplitude and quadrature phase electro-magnetic wave to an antenna.

2. The hybrid coupler of claim 1, wherein the stripline comprises a suspended-stripline, SSL.

3. The hybrid coupler of claim 1, wherein the stripline further comprises an isolated port, and wherein the stripline comprises a base section and four arms electrically connecting the base section with the input port, the two output ports and the isolated port of the stripline, respectively.

4. The hybrid coupler of claim 3, wherein each of the four arms of the stripline comprises one or more matching elements, and wherein the one or more matching elements are configured to match the stripline to the rectangular waveguide transition.

5. The hybrid coupler of claim 3, wherein two arms of the four arms connecting the base section with the input port and the isolated port are shaped symmetrically to another two arms of the four arms connecting the base section with the two output ports.

6. The hybrid coupler of claim 3, wherein the base section of the stripline comprises a metal layer formed at the first main surface of the dielectric substrate, the metal layer comprising an opening formed at a center of the base section.

7. The hybrid coupler of claim 1, wherein the dielectric substrate is a printed circuit board comprising at least one of a top side metallization and a bottom side metallization; and wherein the stripline is formed as an etched signal trace within the top side metallization or the bottom side metallization of the printed circuit board.

8. The hybrid coupler of claim 7, further comprising: an upper ground plane arranged above the first main surface of the dielectric substrate outside an area of the dielectric substrate forming the input port and the two output ports of the stripline; a lower ground plane arranged below the second main surface of the dielectric substrate outside the area of the dielectric substrate forming the input port and the two output ports of the stripline; and a series of vias electrically connecting the upper ground plane with the lower ground plane.

9. The hybrid coupler of claim 1, wherein the rectangular waveguide transition is formed to transmit the equally splitted amplitude and quadrature phase electro-magnetic wave in a direction orthogonal to the first main surface of the stripline.

10. The hybrid coupler of claim 1, wherein the rectangular waveguide transition is formed to transmit the equally splitted amplitude and quadrature phase electro-magnetic wave in a direction parallel to the first main surface of the stripline.

11. The hybrid coupler of claim 1, wherein the rectangular waveguide transition is formed to transmit the equally splitted amplitude and quadrature phase electro-magnetic wave in a direction in between an orthogonal direction of the first main surface of the stripline and a parallel direction of the first main surface of the stripline.

12. The hybrid coupler of claim 1, wherein the rectangular waveguide transition comprises a plurality of stepped waveguide transition sections, each stepped waveguide transition section of the plurality of stepped waveguide transition sections are attached to a respective port of the input port and the two output ports of the stripline.

13. The hybrid coupler of claim 12, wherein the rectangular waveguide transition comprises a plurality of double-ridged waveguide transition sections, each double-ridged waveguide transition section of the plurality of double-ridged waveguide transition sections are attached to a respective port of the input port and the two output ports of the stripline.

14. The hybrid coupler of claim 1, wherein the rectangular waveguide transition comprises a plurality of double-ridged waveguide transition sections, each double-ridged waveguide transition section of the plurality of double-ridged waveguide transition sections are attached to a respective port of the input port and the two output ports of the stripline.

Description

DRAWINGS

[0069] In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

[0070] FIG. 1 shows a perspective view of a schematic diagram illustrating a 3D structure of a hollow rectangular directional hybrid coupler according to one form of the present disclosure;

[0071] FIG. 2 shows a perspective view of a schematic diagram illustrating a 3D structure of a hybrid coupler according to the present disclosure;

[0072] FIG. 3 shows a top view of a schematic diagram illustrating the top side of the substrate of the directional coupler according to the present disclosure;

[0073] FIG. 4 shows a perspective view of a schematic diagram illustrating a 3D structure of a hybrid coupler according to another implementation of the present disclosure;

[0074] FIG. 5A shows a performance diagram illustrating S-parameters of the hybrid coupler shown in FIG. 4;

[0075] FIG. 5B shows a performance diagram illustrating an axial ratio (AR) of the hybrid coupler shown in FIG. 4;

[0076] FIG. 6 shows a schematic diagram illustrating an example of a typical branch line hybrid coupler according to the present disclosure; and

[0077] FIG. 7 shows a performance diagram illustrating an axial ratio plot of the branch line hybrid coupler shown in FIG. 6 compared to the novel hybrid coupler shown in FIG. 4.

[0078] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

[0079] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0080] In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

[0081] It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

[0082] FIG. 1 shows a schematic diagram illustrating a 3D structure of a hollow rectangular directional hybrid coupler 100.

[0083] The hollow rectangular directional hybrid coupler 100 has an input port 101, an isolated port 104, a through port 102 and a coupled port 103.

[0084] Such a design has several couplers in cascade and uses impedance matching steps to obtain RF wideband performance.

[0085] The hybrid coupler 100 is a 3 db directional coupler which couples the power that flows in one direction. It is a 4-port device that splits the power between the output ports 103, 102 (Coupled/Through) in a way that they have a quasi-equal amplitude but a phase difference of 90? between them while at the same time achieving a high isolation between the input ports 101, 104.

[0086] However, the hybrid coupler 100 is a compact device that uses a large volume and has a high mass. In this disclosure, a novel hybrid coupler design is presented that reduces the size and mass of the hybrid coupler 100. The design is presented in FIGS. 2 to 4. Performance of the novel design is shown in FIGS. 5 and 7.

[0087] FIG. 2 shows a schematic diagram illustrating a 3D structure of a hybrid coupler 200 according to the disclosure.

[0088] The hybrid coupler 200 comprises mainly of two parts; an SSL Hybrid Coupler plus four SSL to rectangular waveguide transitions. FIG. 2 is a general 3D view of the hybrid structure showing the waveguide geometry and the SSL PCB inside.

[0089] The hybrid coupler 200 can be used for transmitting equally splitted amplitude and quadrature phase electro-magnetic waves.

[0090] The hybrid coupler 200 comprises a dielectric substrate 300 having a first main surface 300a and a second main surface 300b opposing the first main surface 300a. The dielectric substrate 300 is shown in detail in FIG. 3.

[0091] The hybrid coupler 200 comprises a stripline 330 placed at the first main surface 300a of the dielectric substrate 300. It is understood that the stripline 330 can alternatively also be placed at the second main surface 300b. The stripline 330 comprises an input port 301, isolated port 304 and two output ports 302, 303. The stripline 330 is formed to provide an equally splitted amplitude and quadrature phase electro-magnetic wave at the output ports 302, 303 based on an input signal received at the input port 301.

[0092] The hybrid coupler 200 comprises a rectangular waveguide transition 310 attached to both of the main surfaces 300a, 300b of the substrate 300. The waveguide transition 310 is configured to transmit the electro-magnetic wave to an antenna or to the next device. In FIG. 2, the waveguide transition 310 may have four portions, each one attached to a respective port of the hybrid coupler 200. On the opposite side of 310 is a double ridge waveguide Backshort.

[0093] The stripline 330 may comprise a suspended-stripline, SSL 320 as shown in the design of FIG. 2. However, a stripline 330 without SSL can also be realized.

[0094] The stripline 330 further comprises an isolated port 304 as shown in FIG. 2.

[0095] The stripline 330 may comprise a base section 335 and four arms 331, 332, 333, 334 as shown in more detail in FIG. 3, the arms 331, 332, 333, 334 electrically connecting the base section 335 with the input port 301, the two output ports 302, 303 and the isolated port 304 of the stripline 330, respectively.

[0096] Each of the four arms 331, 332, 333, 334 of the stripline 330 may comprise one or more matching elements 332a, 332b, 333a, 333b as shown in more detail in FIG. 3. The one or more matching elements 332a, 332b, 333a, 333b, may be configured to match the stripline 330 to the waveguide transition 310 as well as impedance matching of the SSL hybrid itself.

[0097] The hybrid coupler 200 has a symmetrical design. The two arms 331, 334 of the four arms 331, 332, 333, 334 connecting the base section 335 with the input port 301 and the isolated port 304 may be shaped symmetrically to the other two arms 332, 333 of the four arms 331, 332, 333, 334 connecting the base section 335 with the two output ports 302, 303.

[0098] The base section 335 of the stripline 330 may comprise a metal layer formed at the first main surface 330a of the dielectric substrate 300. This metal layer may comprise an opening 336 formed at a center of the base section 335 as shown in more detail in FIG. 3.

[0099] The substrate 300 can be a printed circuit board comprising a top side metallization and/or a bottom side metallization. The stripline 330 may be formed as an etched signal trace within the top side metallization or the bottom side metallization of the printed circuit board.

[0100] The hybrid coupler 200 may comprise an upper ground plane 321 arranged above the first main surface 300a of the substrate 300 outside an area 337 of the substrate 300 forming the input and output ports of the stripline 330 as shown in more detail in FIG. 4.

[0101] The hybrid coupler 200 may comprise a lower ground plane 322 arranged below the second main surface 300b of the substrate 300 outside the area 337 of the substrate 300 forming the input and output ports of the stripline 330 as shown in more detail in FIG. 4. A series of vias may electrically connect the upper ground plane with the lower ground plane (not shown).

[0102] The waveguide transition 310 may be formed to transmit the equally splitted amplitude and quadrature phase electro-magnetic wave in a direction orthogonal or parallel to the first main surface 300a of the stripline 330 or in a direction in between the orthogonal and parallel direction. FIG. 2 shows the configuration where the EM-wave is transmitted orthogonal to the first main surface 300a (and also to the second main surface 300b). FIG. 4 shows the configuration where the EM-wave is transmitted parallel to the first main surface 300a (and also to the second main surface 300b).

[0103] The waveguide transition 310 may comprise a plurality of stepped waveguide transition sections 311, 312, 313, 314 as shown in FIG. 4. Each stepped waveguide transition section 311, 312, 313, 314 may be attached to a respective port 301, 302, 303, 304 of the stripline 330.

[0104] The waveguide transition 310 may comprise a plurality of double-ridged waveguide transition sections 315. Each double-ridged waveguide transition section 315 may be attached to a respective port 301, 302, 303, 304 of the stripline 330, as shown in FIG. 2 for example.

[0105] FIG. 3 shows a schematic diagram illustrating the top side 300a of the substrate 300 of the directional coupler 200.

[0106] In FIG. 3 an example of an SSL Layout is shown with the hybrid structure and transmission line matching elements, and E-Field probe to launch RF energy into the waveguide.

[0107] As described above with respect to FIG. 2, the hybrid coupler 200 comprises a dielectric substrate 300 having a first main surface 300a and a second main surface 300b opposing the first main surface 300a. FIG. 3 shows the first main surface 300a of the dielectric substrate 300.

[0108] The stripline 330 is placed at the first main surface 300a of the dielectric substrate 300. The stripline 330 comprises an input port 301 and two output ports 302, 303. The stripline 330 is formed to provide an equally splitted amplitude and quadrature phase electro-magnetic wave at the output ports 302, 303 based on an input signal received at the input port 301.

[0109] The stripline 330 may comprise a suspended-stripline, SSL 320 as shown here in the example of FIG. 3. However, a stripline 330 without SSL can also be realized.

[0110] The stripline 330 further comprises an isolated port 304 as shown in FIG. 2.

[0111] The stripline 330 comprises a base section 335 and four arms 331, 332, 333, 334. The arms are electrically connecting the base section 335 with the input port 301, the two output ports 302, 303 and the isolated port 304 of the stripline 330, respectively.

[0112] Each of the four arms 331, 332, 333, 334 comprise a plurality of matching elements 332a, 332b, 333a, 333b etc. as shown in FIG. 3. The matching elements 332a, 332b, 333a, 333b are configured to match the stripline 330 to the waveguide transition 310.

[0113] As can be seen from FIG. 3, the hybrid coupler 200 and thus also the substrate 300 and the stripline 330 have a symmetrical design. The two arms 331, 332 of the four arms 331, 332, 333, 334 connecting the base section 335 with the input port 301 and the isolated port 304 are shaped symmetrically to the other two arms 333, 334 of the four arms 331, 332, 333, 334 connecting the base section 335 with the two output ports 302, 303.

[0114] The base section 335 of the stripline 330 may comprise a metal layer, e.g., made of Copper, formed at the first main surface 330a of the dielectric substrate 300. This metal layer comprises an opening 336 formed at a center of the base section 335.

[0115] The substrate 300 can be a printed circuit board with top side metallization and/or a bottom side metallization. The stripline 330 can be formed as an etched signal trace within the top side metallization or the bottom side metallization of the printed circuit board.

[0116] In the SSL design as shown in FIGS. 2 and 3, an upper ground plane 321 (see FIG. 4) can be arranged above the first main surface 300a of the substrate 300 outside an area 337 of the substrate 300 forming the input and output ports of the stripline 330. A lower ground plane 322 (see FIG. 4) can be arranged below the second main surface 300b of the substrate 300 outside the area 337 of the substrate 300 forming the input and output ports of the stripline 330.

[0117] FIG. 4 shows a schematic diagram illustrating a 3D structure of a hybrid coupler 400 according to another implementation.

[0118] FIG. 4 particularly shows one of several possible configurations to connect the hybrid.

[0119] The hybrid coupler 400 comprises a dielectric substrate 300 that may be formed as described above with respect to FIG. 3.

[0120] A rectangular waveguide transition 310 is attached to both of the main surfaces 300a, 300b of the substrate 300. Here in FIG. 4, the waveguide transition 310 has four portions which are attached to both main surfaces 300a, 300b of the substrate 300. Each portion is attached to a respective port of the hybrid coupler 400. The waveguide transition 310 is configured to transmit the equally splitted amplitude and quadrature phase electro-magnetic wave to an antenna.

[0121] The stripline 330 may comprise or may be a suspended-stripline, SSL 320 as can be seen from FIG. 4. As described above, also a design without SSL where the waveguide transition 310 is directly attached to the substrate 300, e.g., PCB can be implemented (not shown).

[0122] The stripline 330 further comprises an isolated port 304.

[0123] As described above, the design of the stripline 330 may correspond to the design shown in FIG. 3.

[0124] The substrate 300 can be a printed circuit board comprising a top side metallization and/or a bottom side metallization. As described above, the stripline 330 may be formed as an etched signal trace within the top side metallization or the bottom side metallization of the printed circuit board.

[0125] The hybrid coupler 400, in particular the SSL 320, may comprise an upper ground plane 321 arranged above the first main surface 300a of the substrate 300 outside an area 337 (shown in FIG. 3) of the substrate 300 forming the input and output ports of the stripline 330. The hybrid coupler 400 may comprise a lower ground plane 322 arranged below the second main surface 300b of the substrate 300 outside the area 337 of the substrate 300 forming the input and output ports of the stripline 330. A series of vias may electrically connect the upper ground plane with the lower ground plane (not shown).

[0126] The waveguide transition 310 may be formed to transmit the equally splitted amplitude and quadrature phase electro-magnetic wave in a direction orthogonal or parallel to the first main surface 300a of the stripline 330 or in a direction in between the orthogonal and parallel direction. FIG. 4 shows the configuration where the EM-wave is transmitted parallel to the first main surface 300a (and also to the second main surface 300b).

[0127] The waveguide transition 310 comprises a plurality of stepped waveguide transition sections 311, 312, 313, 314. Each stepped waveguide transition section 311, 312, 313, 314 may be attached to a respective port 301, 302, 303, 304 of the stripline 330. These stepped waveguide transition sections 311, 312, 313, 314 are attached to the first main surface 300a of the substrate 300 (top side) as can be seen from FIG. 4.

[0128] The waveguide transition 310 comprises a plurality of double-ridged waveguide transition sections 315. Each double-ridged waveguide transition section 315 may be attached to a respective port 301, 302, 303, 304 of the stripline 330. These double-ridged waveguide transition sections 311, 312, 313, 314 are attached to the second main surface 300b (bottom side) of the substrate 300 as can be seen from FIG. 4.

[0129] FIG. 5A shows a performance diagram 500a illustrating S-parameters of the hybrid coupler 400 shown in FIG. 4.

[0130] In this 4 port device, there are 4 Scattering parameters per port (S-parameters) which represent the incident and reflected power signals for a specific frequency band which can be scaled to other bands.

[0131] The following S-parameters of the hybrid coupler 400 are shown: [0132] S1,1 (graph 504) is the reflection parameter (Input port) [0133] S4,1 (graph 503) is the isolation parameter (Isolated port) [0134] S2,1 (graph 501) and S3,1 (graph 502) are the transmission parameters (Through and Coupled ports).

[0135] The S-parameters show that excellent transmission (graphs 501, 502) and reflection (graphs 503, 504) properties can be achieved with the novel hybrid coupler 400.

[0136] FIG. 5B shows a performance diagram 500b illustrating an axial ratio (AR) of the hybrid coupler 400 shown in FIG. 4.

[0137] Next is Axial Ratio (AR) in dB (graph 505) which is the ratio of two orthogonal electric field components equal in amplitude with 90 degrees phase shift. This is a fundamental performance parameter for any circular polarized antenna. Typical satcom applications desire the axial ratio to be <1 dB.

[0138] As can be seen from FIG. 5B, the novel hybrid coupler 400 can even provide axial ratio less than 0.1 dB.

[0139] FIG. 6 shows a schematic diagram illustrating an example of a typical branch line hybrid coupler 600 without including the waveguide transitions.

[0140] The hybrid coupler has an input port 601, an isolated port 604 and two output ports 602, 603.

[0141] The hybrid coupler 600 splits the power between the output ports 602, 603 (E1 and E2) in a way that they have a quasi-equal amplitude but a phase difference of 90? between them which lead to a circularly polarized wave when connected to an antenna as a result of adding the two electric field vectors together (E1+E2).

[0142] FIG. 7 shows a performance diagram illustrating an axial ratio plot 700 of the branch line hybrid coupler 600 shown in FIG. 6 compared to the novel hybrid coupler 400 shown in FIG. 4.

[0143] The plot 702 of the branch line hybrid coupler 600 indicates a relatively narrow band performance for the desired frequency band. This hybrid coupler design uses fundamental changes and optimization to reach the desired RF performance. Such changes may include cascading multiple couplers to achieve the wide band width for both matching parameters and the axial ratio which consequently will add more area to the overall design.

[0144] The plot 703 corresponds to the plot 505 of FIG. 5B of the novel hybrid coupler design.

[0145] As can be seen from FIG. 7, the plot 703 of the novel hybrid coupler 400 shows excellent performance over the whole frequency band between 26 and 32 GHz. An axial ratio less than 0.1 dB can be provided over this broad frequency band.

[0146] While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms include, have, with, or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term comprise. Also, the terms exemplary, for example and e.g. are merely meant as an example, rather than the best or optimal. The terms coupled and connected, along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

[0147] Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

[0148] Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

[0149] Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the present disclosure beyond those described herein. While the present disclosure has been described with reference to one or more particular forms, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present disclosure. It is therefore to be understood that within the scope of the appended claims and their equivalents, the present disclosure may be practiced otherwise than as specifically described herein.

[0150] Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word about or approximately in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.

[0151] As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean at least one of A, at least one of B, and at least one of C.

[0152] The apparatuses and methods described in this application may be partially or fully implemented by a special purpose computer created by configuring a general-purpose computer to execute one or more particular functions embodied in computer programs. The functional blocks, flowchart components, and other elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer.

[0153] The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.