CN115207583B

CN115207583B - Waveguide quadrature mode converter

Info

Publication number: CN115207583B
Application number: CN202210764468.2A
Authority: CN
Inventors: 陈思丞; 李津; 许志宏; 袁涛
Original assignee: Shenzhen University
Current assignee: Shenzhen University
Priority date: 2022-06-30
Filing date: 2022-06-30
Publication date: 2023-06-06
Anticipated expiration: 2042-06-30
Also published as: CN115207583A

Abstract

The invention provides a waveguide orthogonal analog converter, which comprises a metal shell, wherein the metal shell comprises a polarization separator, two groups of bent waveguides and two power combiners, and the two groups of bent waveguides are respectively connected between the polarization separator and the two power combiners. The polarization separator is used for separating two mutually orthogonal linear polarization waves synchronously transmitted in the same waveguide into two paths of equal-amplitude opposite signals in respective polarization directions, the two groups of curved waveguides transmit the polarized separated signals to the power synthesizer, and the power synthesizer synthesizes the two paths of equal-amplitude opposite signals in each polarization direction into one path. The metal shell is provided with an inner cavity, the inner cavity penetrates through the polarization separator, the two groups of bending waveguides and the two power synthesizers respectively, and the inner cavity is formed by smoothly and continuously enclosing curved surfaces. The invention designs the inner cavity of the metal shell to be formed by smoothly and continuously enclosing the curved surfaces, so that the inner part of the metal shell has no discontinuous structure with any abrupt change, and the process principle of 3-D printing is completely fused.

Description

Waveguide quadrature mode converter

Technical Field

The invention belongs to the technical field of electromagnetic fields and microwaves, and particularly relates to a waveguide quadrature analog converter.

Background

The waveguide orthogonal mode converter is a three-port passive device for synthesizing or separating two mutually orthogonal electromagnetic wave signals, wherein three ports comprise a common port and two independent ports, two orthogonal linear polarized waves are transmitted at the common port, waves in each polarization direction are respectively transmitted at the two independent ports, the two independent ports are mutually isolated, and the two linear polarized waves are mutually isolated. The waveguide orthogonal analog converter can simultaneously and independently transmit two mutually orthogonal linear polarized waves, can serve as the rear end of the dual-polarized waveguide antenna, plays a key role in a satellite communication system, and can improve the channel multiplexing capacity of the satellite-to-ground communication system and the transceiving bandwidth of a communication link. Waveguide quadrature analog converters are mainly classified into three main categories according to the characteristics of the functional structure: side arm (Sidearm), cross-tie (Turnstole) and

knot type, in which the structure of the side arm type is the simplest but it is difficult to achieve broadband radio frequency performance, and cross knot type (turnstine) and +.>

The junction type can realize broadband radio frequency performance, and the core functional structures of the junction type can comprise a polarization separator and a power synthesizer, and the communication of the cavity structures is realized through a plurality of sections of gradually changed bent waveguides.

In the conventional technology, the waveguide quadrature analog converter is generally manufactured by adopting a Computer Numerical Control (CNC) milling or micro machining process according to the application frequency band and the size requirement, and the machining process can achieve higher precision, but has larger limitation in manufacturing a complex structure. A complex waveguide quadrature analog converter often needs to be split into a plurality of parts to be respectively processed and then spliced and assembled, and gaps among the assembled parts and other discontinuous structures caused by processing errors can cause the deterioration of radio frequency performance; meanwhile, the traditional waveguide orthogonal mode converter has the defects of more redundant structural materials, more assembly fasteners and heavy device weight, and is unfavorable for the light weight and the miniaturization of a communication system.

An alternative processing scheme for waveguide quadrature analog converters is additive manufacturing technology, i.e. 3-D printing. Although the traditional waveguide quadrature analog converter can be manufactured and molded by adopting a 3-D printing process, a remarkable contradiction exists between the traditional structure of the waveguide quadrature analog converter and the 3-D printing process, and the compatibility of the traditional waveguide quadrature analog converter and the 3-D printing process is poor, and the traditional waveguide quadrature analog converter is particularly expressed in the following aspects: (1) The waveguide orthogonal analog converter with the inner cavity is difficult to integrate with 3-D printing and forming; (2) The hanging structure in the inner cavity needs to be supported in the 3-D printing process, but the supporting structure in the inner cavity is difficult to remove after the process is finished; (3) the micro-structures such as the membrane in the inner cavity are easy to deform; (4) Deformation caused by 3-D printing materials and processes per se has a great influence on the radio frequency performance of the waveguide quadrature mode converter; (5) The discontinuous structures such as stepped waveguide gradual change of the waveguide orthogonal mode converter have poor surface quality after 3-D printing and molding, and the problems of breakage, printing material residue and the like are easy to occur. For example, four polarization separation ports (rectangular waveguides) and a common port (square waveguide or circular waveguide) of a conventional turnstinle cross are mutually perpendicular in the propagation direction of electromagnetic waves, and a proper printing forming direction must be selected before processing by a 3-D printing process to ensure that the forming of the waveguide quadrature analog converter does not need any internal support, and in general, the forming direction needs to incline the waveguide quadrature analog converter by an angle, and the inclined printing waveguide quadrature analog converter leads to the internal polarization separation and impedance matching enabling structure to deform after forming, so that the symmetry of the enabling structure is destroyed, and the reflection performance and isolation of the waveguide quadrature analog converter are deteriorated.

Disclosure of Invention

The invention aims to provide a waveguide orthogonal mode converter, which solves the technical problems that an inner cavity needs to be supported and is easy to deform when the waveguide orthogonal mode converter is manufactured by adopting a 3-D printing process in the prior art.

In order to achieve the above purpose, the invention adopts the following technical scheme: the waveguide quadrature analog converter comprises a metal shell, wherein the metal shell comprises a polarization separator, two groups of bent waveguides and two power synthesizers; the two groups of the bent waveguides are respectively connected between the polarization separator and the two power synthesizers, the polarization separator is used for separating two mutually orthogonal linear polarized waves synchronously transmitted in the same waveguide into two paths of equal-amplitude inverted signals in respective polarization directions, the two groups of the bent waveguides are respectively used for transmitting the polarized separated signals to the power synthesizers, and the power synthesizers are used for synthesizing the two paths of equal-amplitude inverted signals in each polarization direction into one path; the metal shell is further provided with an inner cavity, the inner cavity penetrates through the polarization separator, the two groups of bent waveguides and the two power combiners respectively, and the inner cavity is formed by enclosing smooth and continuous curved surfaces.

In one possible design, each set of the curved waveguides includes two curved waveguides for transmitting two equal-amplitude inverted signals in each polarization direction, respectively; the cross section of the inner cavity of the metal shell along the transmission direction perpendicular to the linear polarized wave is a first cross section, and in the metal shell, at least the outline of the inner cavity of the curved waveguide along the first cross section is a symmetrical closed curve, and the first cross section is perpendicular to the transmission direction of the linear polarized wave; the symmetrical closed curves are symmetrical structures along two mutually perpendicular directions of the first section, and the maximum lengths of the symmetrical closed curves along the two mutually perpendicular directions of the first section are different.

In one possible design, the symmetrical closed curve is elliptical.

In one possible design, the polarization separator comprises a main waveguide, a polarization separation cavity and two groups of waveguides, wherein the main waveguide is communicated with one side of the polarization separation cavity, and the two groups of waveguides are respectively communicated with the other side of the polarization separation cavity; the polarization separation cavity is used for separating two mutually orthogonal linear polarization waves synchronously transmitted in the main waveguide into two paths of signals with equal amplitude and opposite phase in respective polarization directions, and transmitting the signals to the two groups of curved waveguides through the two groups of split waveguides respectively;

wherein the polarization separator has axisymmetric structures along two polarization directions;

and/or the polarization separator is in a rotationally symmetrical structure.

In one possible design, the angle between the central axis of the split waveguide and the central axis of the main waveguide is between 90 degrees and 150 degrees;

and/or the central axial surfaces of the two groups of the sub-waveguides are mutually perpendicular.

In one possible design, the bottom center of the polarization separation cavity has a shaped circular truncated cone for polarization separation and impedance matching.

In one possible design, the shaping round table is circular along a second section perpendicular to the main waveguide central axis, the shaping round table includes a plurality of round structures, a plurality of round structures are stacked in sequence from bottom to top, a plurality of second section areas of the round structures are in a decreasing trend from bottom to top, and at least one round structure located in the middle is in a round table shape.

In one possible design, the power combiner includes two connection waveguides and a combination waveguide, the two connection waveguides and the combination waveguide are connected in a Y shape, and the power combiner has a symmetrical structure.

In one possible design, the two central axes of the connecting waveguides respectively form an angle of between 90 and 150 degrees with the central axis of the combining waveguide;

and/or the included angle between the central axes of the two power synthesizers is between 0 and 90 degrees;

and/or, the central axis of at least one power combiner coincides with the central axis of the polarization separator.

In one possible design, the center of the end of the inner junction of the two connecting waveguides is formed with a curved notch.

In one possible design, the end of the polarization separator far away from the power combiner and the ends of the two power combiners far away from the polarization separator are both provided with waveguide flanges;

and the polarization separator is communicated with the waveguide flange plate and the power combiner is communicated with the waveguide flange plate through transition waveguides.

The waveguide quadrature analog converter provided by the invention has the beneficial effects that: compared with the prior art, the waveguide orthogonal mode converter is formed by designing the inner cavity of the metal shell to be surrounded by smooth and continuous curved surfaces, so that the interior of the metal shell has no discontinuous structure with any abrupt change, the 3-D printing process principle is completely fused, the compatibility of the metal shell and the 3-D printing process is extremely high, and the reliability of integrally manufacturing the waveguide orthogonal mode converter by adopting the 3-D printing process is improved. In particular, the polarization separator and the power synthesizer are shaped, so that the metal shell is easier to integrally manufacture and form under the condition of using a minimum supporting structure, symmetry of a key structure is not damaged when the cavity is formed, deterioration of radio frequency performance caused by the cavity shape is reduced, meanwhile, risks of damage and collapse of the cavity wall in the 3-D printing process are reduced, smooth continuous curved surface contours are formed, and radio frequency loss caused by surface roughness is reduced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a perspective view of a waveguide quadrature analog converter according to an embodiment of the present invention, in which fig. 1 (a) is a perspective view for radio frequency measurement in a vertical polarization direction, and fig. 1 (b) is a perspective view for radio frequency measurement in a horizontal polarization direction;

FIG. 2 is a perspective view of a waveguide quadrature analog converter in another direction according to an embodiment of the present invention;

FIG. 3 is a perspective cross-sectional view of the waveguide quadrature analog converter of FIG. 2 along the center plane Y-Y;

FIG. 4 is a perspective cross-sectional view of the waveguide quadrature analog converter of FIG. 2 along a center plane X-X;

FIG. 5 is an enlarged view of a portion of the shaped circular table of the polarization separator in the dashed box of FIG. 3 (region A);

FIG. 6 is an enlarged view of a portion of the shaped circular table of the polarization separator in the dashed box of FIG. 4 (region C);

fig. 7 is an enlarged view of a portion of the "arch-shaped" cavity wall of the power combiner of fig. 3 in dashed box (region B);

FIG. 8 is an enlarged partial view of the "arch-shaped" cavity wall of the power combiner of the dashed box of FIG. 4 (region D);

FIG. 9 is a schematic perspective view of the polarization splitter, first transition waveguide and first waveguide flange of FIG. 1;

FIG. 10 is a schematic perspective view of the power combiner, second transition waveguide and second waveguide flange of FIG. 1;

FIG. 11 is a graph of simulated scattering parameters for a polarization splitter of a waveguide quadrature mode converter according to an embodiment of the present invention;

FIG. 12 is a graph of simulated scattering parameters of a power combiner of a waveguide quadrature analog-to-digital converter according to an embodiment of the present invention;

FIG. 13 is a graph of simulated scattering parameters of a transition waveguide of a waveguide quadrature mode converter according to an embodiment of the present invention, wherein FIG. 13 (a) is a graph of simulated scattering parameters of a first transition waveguide and FIG. 13 (b) is a graph of simulated scattering parameters of a second transition waveguide;

FIG. 14 is a graph of simulated scattering parameters for an air cavity model of a waveguide quadrature mode converter (without a first transition waveguide) provided by an embodiment of the present invention;

FIG. 15 (a) shows the simulation and measured scattering parameters (S) of a waveguide quadrature mode converter (including a first transition waveguide) in a vertical polarization direction according to an embodiment of the present invention ^V ₁₁ And S is ^V ₂₁ ) A graph;

FIG. 15 (b) shows a simulation of the waveguide quadrature mode converter (including the first transition waveguide) in the horizontal polarization direction and the measured scattering parameters (S) ^H ₁₁ And S is ^H ₃₁ ) A graph;

fig. 15 (c) shows the transmission coefficient S in fig. 15 (a) and 15 (b) ^V ₂₁ And S is ^H ₃₁ Is a zoomed-in view of (a);

FIG. 15 (d) is a schematic illustration of a waveguide quadrature mode converter (including a first transition waveguide) for S-measurements in accordance with an embodiment of the present invention ^V ₃₁ 、S ^H ₂₁ And S is ₂₃ And a parameter graph representing polarization isolation and port isolation of the device.

Wherein, each reference sign in the figure:

1. a metal housing; 10. a polarization separator; 11. a main waveguide; 12. a polarization separation cavity; 13. a branching waveguide; 15. a second port; 16. shaping the round table; 161. a hemispherical top surface; 162. a small cylinder; 163. a high round table; 164. flat round table; 165. a flat cylinder; 20. bending the waveguide; 30. a power combiner; 31. a connecting waveguide; 32. a coupling waveguide; 33. a third port; 35. an arch-shaped cavity wall; 36. a curved surface notch; 40. A first transition waveguide; 50. a second transition waveguide; 60. a first waveguide flange; 61. a rectangular waveguide port; 62. a through hole; 70. and a second waveguide flange.

Detailed Description

In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are merely for convenience in describing and simplifying the description based on the orientation or positional relationship shown in the drawings, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the description of the embodiments of the present invention, given that the structural dimensions are preferred parameters, the dimensional parameters of each component may be modified to further obtain the actually required performance with reference to the embodiments of the present invention.

Referring to fig. 1, fig. 1 is a perspective view of a waveguide quadrature analog converter according to an embodiment of the present invention, where fig. 1 (a) is a perspective view of a vertical polarization direction radio frequency measurement, and fig. 1 (b) is a perspective view of a horizontal polarization direction radio frequency measurement; the waveguide quadrature mode converter comprises a metal shell 1, wherein the metal shell 1 comprises a polarization separator 10, two groups of bent waveguides 20 and two power combiners 30; the two groups of curved waveguides 20 are respectively connected between the polarization separator 10 and the two power synthesizers 30, the polarization separator 10 is used for separating two mutually orthogonal linear polarized waves synchronously transmitted in the same waveguide into two paths of equal-amplitude inverted signals in respective polarization directions, the two groups of curved waveguides 20 are respectively used for transmitting the polarized separated signals to the power synthesizers 30, and the power synthesizers 30 are used for synthesizing the two paths of equal-amplitude inverted signals in each polarization direction into one path; the curved waveguide 20 is connected with the polarization splitter 10 in a smooth and continuous manner, and the curved waveguide 20 is connected with the power combiner 30 in a smooth and continuous manner. The metal housing 1 also has an inner cavity, which penetrates the polarization splitter 10, the two sets of curved waveguides 20 and the two power combiners 30, respectively, and which is formed by smoothly and continuously enclosing curved surfaces. In summary, the metal shell 1 does not have any abrupt discontinuous structure inside, and the inner cavity profile is a smooth curved surface.

According to the waveguide quadrature analog converter provided by the embodiment of the invention, the inner cavity of the metal shell 1 is designed to be formed by smoothly and continuously enclosing the curved surface, so that the interior of the metal shell 1 has no discontinuous structure with any abrupt change, the process principle of 3-D printing is completely fused, the compatibility of the metal shell 1 and the 3-D printing process is extremely high, and the reliability of integrally manufacturing the waveguide quadrature analog converter by adopting the 3-D printing process is improved. In particular, the polarization separator 10 and the power combiner 30 are shaped, so that the metal housing 1 is easier to integrally manufacture and form under the condition of using a minimum support structure, key structural symmetry is not destroyed when the cavity is formed, deterioration of radio frequency performance caused by cavity shape variation is reduced, meanwhile, risks of breakage and collapse of the cavity wall in the 3-D printing process are reduced, and the formed smooth continuous curved surface profile is also beneficial to reducing radio frequency loss caused by surface roughness.

In one embodiment, referring to fig. 1, each set of curved waveguides 20 includes two curved waveguides 20, where the two curved waveguides 20 are disposed opposite each other, and the two curved waveguides 20 are used to transmit two equal-amplitude inverted signals in each polarization direction. The cross section of the inner cavity of the metal housing 1 along the direction perpendicular to the transmission direction of the linearly polarized wave is a first cross section, and in the metal housing 1, at least the profile of the inner cavity of the curved waveguide 20 along the first cross section is a symmetrical closed curve. The symmetrical closed curves are symmetrical structures along two mutually perpendicular directions of the first section, and the maximum lengths of the symmetrical closed curves along the two mutually perpendicular directions of the first section are different.

It should be noted that, at least the profile of the inner cavity of the curved waveguide 20 along the first cross section is a symmetrical closed curve, which means that the first cross section of the four curved waveguides 20 may be a symmetrical closed curve, or the four curved waveguides 20, the non-abrupt part in the polarization splitter 10, and the non-abrupt part in the power combiner 30 may be symmetrical closed curves.

Preferably, the symmetrical closed curve is elliptical, so that the traditional rectangular section metal shell is converted into the metal shell 1 formed by continuously connecting smooth curves while the broadband radio frequency performance is ensured, and the compatibility of the shell structure to a 3-D printing process is remarkably improved. It should be understood that in other embodiments of the present invention, the symmetrical closed curve may be an elliptic curve with various cross-sectional dimensions, or may be other symmetrical closed curves that satisfy the transmission of electromagnetic waves in the waveguide, and is not particularly limited herein.

In one embodiment, referring to fig. 1, the end of the polarization splitter 10 away from the power combiner 30 and the ends of the two power combiners 30 away from the polarization splitter 10 are each provided with a waveguide flange. Specifically, for convenience of the following description, different waveguide flanges are distinguished, for example, one end of the polarization splitter 10 away from the power combiner 30 is provided with a first waveguide flange 60, and one end of the two power combiners 30 away from the polarization splitter 10 is provided with a second waveguide flange 70. The waveguide flange is provided with rectangular waveguide ports 61 and through holes 62 for connection with an external circuit assembly.

In one embodiment, referring to FIG. 1, the polarization splitter 10 is in communication with the waveguide flange and the power combiner 30 is in communication with the waveguide flange via transition waveguides. Specifically, the polarization splitter 10 is communicated with the first waveguide flange 60 through the first transition waveguide 40, and the power combiner 30 is communicated with the second waveguide flange 70 through the second transition waveguide 50.

In one embodiment, please refer to fig. 1 to 6 and fig. 9, fig. 2 is a perspective view of another direction of a waveguide orthomode converter according to an embodiment of the present invention, fig. 3 is a perspective cross-sectional view of the waveguide orthomode converter along a central plane Y-Y in fig. 2, fig. 4 is a perspective cross-sectional view of the waveguide orthomode converter along a central plane X-X in fig. 2, fig. 5 is a partially enlarged view of a shaping circular table of a polarization separator in a dashed frame (region a) in fig. 3, fig. 6 is a partially enlarged view of a shaping circular table of a polarization separator in a dashed frame (region C) in fig. 3, and fig. 9 is a perspective schematic view of the polarization separator, a first transition waveguide and a first waveguide flange in fig. 1. The polarization splitter 10 functions to split two mutually orthogonal linearly polarized waves synchronously transmitted in the same waveguide into two equal-amplitude inverted signals in the respective polarization directions. The polarization separator 10 comprises a main waveguide 11, a polarization separation cavity 12 and two component waveguides 13, wherein the main waveguide 11 is communicated with one side of the polarization separation cavity 12, and the two component waveguides 13 are respectively communicated with the other side of the polarization separation cavity 12. The polarization separation cavity 12 is used for separating two mutually orthogonal linear polarized waves synchronously transmitted in the main waveguide 11 into two paths of signals with equal amplitude and opposite phases in respective polarization directions, and transmitting the signals to the two groups of curved waveguides 20 through the two groups of waveguides 13. Each group of the waveguides 13 comprises two opposite waveguides 13, each group of the curved waveguides 20 comprises two opposite curved waveguides 20, four waveguides 13 are respectively communicated with the other side of the polarization separation cavity 12, and four curved waveguides 20 are respectively communicated with the four waveguides 13 in a one-to-one correspondence.

The polarization separator 10 has an axisymmetric structure along two polarization directions, and the polarization separator 10 has a rotationally symmetric structure, that is, four waveguides 13 are uniformly distributed on the other side of the polarization separation cavity 12 along the circumferential direction, and the symmetrical structure design makes the polarization directions of electromagnetic waves keep orthogonal in the polarization separation process, so that the polarization isolation is maintained at a higher level.

Preferably, the central axes of the four sub-waveguides 13 form an angle of 135 degrees with the central axis of the main waveguide 11. It should be understood that, in other embodiments of the present invention, the central axis of the split waveguide 13 may form any angle between 90 degrees and 150 degrees with the central axis of the main waveguide 11, which is not limited herein. The central axial surfaces of the two component waveguides 13 are mutually vertical, so that signals in the vertical and horizontal polarization directions are respectively and independently transmitted without mutual influence.

The polarization splitter 10 has five ports, a first port (not identified in the figure) where the main waveguide 11 is distant from the branch waveguide 13 and four second ports 15 where the branch waveguide 13 is distant from the main waveguide 11. The first port is circular, the rectangular waveguide port 61 of the first waveguide flange 60 is rectangular, the first transition waveguide 40 is a transition structure with a first section gradually changing from rectangular to circular, the first transition waveguide 40 is a bidirectional symmetrical structure, and the inner surface of the first transition waveguide 40 is a smooth curved surface.

The first section of the main waveguide 11 is circular, and the first section of the polarization splitter 10 is also circular, and the caliber gradually increases, so that the division of the four sub-waveguides 13 is facilitated. The first cross section of the four sub-waveguides 13 is elliptical, the four second ports 15 are elliptical, and the first cross section of the four sub-waveguides 13 is the same size as the first cross section of the four curved waveguides 20.

In one embodiment, the polarization separator 10 is formed by shaping a traditional waveguide cross junction based on an elliptical waveguide architecture, the polarization separation cavity 12 is formed by stacking a circular truncated cone cavity and a cylindrical cavity, the bottom center of the polarization separation cavity 12 is provided with a shaping circular truncated cone 16, the shaping circular truncated cone 16 is used for polarization separation and impedance matching, that is, two mutually orthogonal linear polarized waves transmitted synchronously are separated into signals in two vertical and horizontal polarization directions by the shaping circular truncated cone 16, and two paths of equal power distribution are performed in each polarization direction.

Specifically, the molding round table 16 is circular along the second section perpendicular to the central axis of the main waveguide 11, the molding round table 16 includes a plurality of round structures, the plurality of round structures are sequentially stacked from bottom to top, the second section area of the plurality of round structures is in a decreasing trend from bottom to top, and at least one round structure located in the middle is in a round table shape. In summary, the molding round table 16 is a round shrinkage structure from bottom to top, so the design makes the inner surface of the polarization separation cavity 12 be a continuous smooth curved surface, which is highly compatible with the 3-D printing process, and is also beneficial to separating and distributing signals in the vertical and horizontal polarization directions.

Preferably, referring to fig. 6, the molding round table 16 includes five round structures, which are stacked in sequence from bottom to top, specifically: the novel semi-sphere comprises an oblate column 165, an oblate table 164, a high round table 163, a small cylinder 162 and a semi-sphere top surface 161, wherein the outer diameter of the bottom end of the oblate table 164 is equal to the outer diameter of the oblate column 165, the outer diameter of the top end of the oblate table 164 is equal to the outer diameter of the bottom end of the high round table 163, the outer diameter of the top end of the high round table 163 is equal to the outer diameter of the small cylinder 162, and the radius of the semi-sphere top surface 161 is equal to the radius of the small cylinder 162. It will be appreciated that in other embodiments of the present invention, the number of the above-mentioned round structures may be one, two, three or more, according to the design specification, and is not particularly limited herein.

In one embodiment, referring to fig. 10, fig. 10 is a schematic perspective view of the power combiner, the second transition waveguide and the second waveguide flange of fig. 1. The power combiner 30 is configured to re-combine the two equal-amplitude inverted signals in each polarization direction into one path. The power combiner 30 includes two connecting waveguides 31 and a combining waveguide 32, the two connecting waveguides 31 are Y-shaped connected with the combining waveguide 32, and the power combiner 30 has a symmetrical structure.

Specifically, the power combiner 30 includes two third ports 33 and a fourth port (not shown), where the two third ports 33 are respectively connected to the two curved waveguides 20, and the fourth port is connected to the rectangular waveguide port 61 of the second waveguide flange 70 through the second transition waveguide 50. Both the third port 33 and one fourth port are elliptical in shape, and the elliptical profile of the third port 33 is the same as the elliptical profile of the curved waveguide 20. The second transition waveguide 50 has a bidirectional symmetrical structure in which an elliptical cross section gradually changes to a rectangular cross section, and the inner surface of the second transition waveguide 50 is a smooth curved surface.

Preferably, the central axes of the two connecting waveguides 31 are each at 135 degrees from the central axis of the combining waveguide 32. It will be appreciated that in other embodiments of the present invention, the central axes of the two connecting waveguides 31 may form any angle between 90 degrees and 150 degrees with the central axis of the combining waveguide 32, which is not particularly limited herein.

Preferably, the central axes of the two power combiners 30 are at a 45 degree angle. It is understood that in other embodiments of the present invention, the central axes of the two power synthesizers 30 may form any angle between 0 degrees and 90 degrees, which is not particularly limited herein.

The central axis of at least one power combiner 30 coincides with the central axis of the polarization splitter 10. Preferably, in this embodiment, the central axis of one power combiner 30 coincides with the central axis of the polarization splitter 10, and the central axis of the other power combiner 30 forms an angle of 45 degrees with the central axis of the polarization splitter 10.

In one embodiment, referring to fig. 2, 4, 7 and 8, fig. 7 is an enlarged partial view of the "arched door-shaped" cavity wall of the power combiner in the dashed box (region B) of fig. 4, and fig. 8 is an enlarged partial view of the "arched door-shaped" cavity wall of the power combiner in the dashed box (region D) of fig. 4. The center of the end of the inner junction of the two connecting waveguides 31 of the power combiner 30 is formed with a curved notch 36. Specifically, the overlapping of the two sections of connecting waveguides 31 forms an "arched door-shaped" cavity wall 35, so as to further reduce the risk of breakage and collapse of the "arched door-shaped" cavity wall 35 during the 3-D printing process, a small section of cylinder is symmetrically excavated at the top end of the "arched door-shaped" cavity wall 35 on the premise of not affecting the radio frequency performance of the power combiner 30, and rounded edges of the excavated cavity are processed to form curved surface notches 36.

In one embodiment, referring to fig. 1, the central axis of the first transition waveguide 40 is arranged in line with the central axis of the polarization splitter 10, and the main mode electric field direction of the rectangular waveguide port 61 is parallel to the electric field direction of one linearly polarized wave in the polarization splitter 10 and perpendicular to the electric field direction of the other linearly polarized wave.

In one embodiment, after passing through the polarization splitter 10, the two orthogonal linear polarized waves at the first port are equally divided into two opposite signals in each polarization direction, wherein the upper and lower curved waveguides 20 respectively transmit half-power vertical polarized waves, and the left and right curved waveguides 20 respectively transmit half-power horizontal polarized waves. The upper and lower signals are transmitted through the upper and lower curved waveguides 20, recombined into a vertical polarized wave through the power combiner 30, and output to the rectangular waveguide port 61 of the second waveguide flange 70 through the second transition waveguide 50 in the horizontal direction; the left and right signals are transmitted through the left and right curved waveguides 20, recombined into a horizontal polarized wave through the power combiner 30, and output to the rectangular waveguide port 61 of the second waveguide flange 70 through the second transition waveguide 50 inclined at 45 degrees.

When the first transition waveguide 40 as shown in fig. 1 (a) is adopted, only vertical polarized waves can be excited at the first port, and the vertical polarized waves are output by the rectangular waveguide port 61 of the second waveguide flange 70 in the horizontal direction, and the rectangular waveguide port 61 of the second waveguide flange 70 in the 45-degree oblique direction is isolated; when the first transition waveguide 40 is used as shown in fig. 1 (b), only horizontally polarized waves can be excited at the first port, and the horizontally polarized waves are output by the rectangular waveguide port 61 of the second waveguide flange 70 in the 45-degree oblique direction, and the rectangular waveguide port 61 of the second waveguide flange 70 in the horizontal direction is isolated; the rectangular waveguide ports 61 of the second waveguide flange 70 in the horizontal direction and the 45-degree oblique direction are always kept isolated from each other. In order to obtain a high degree of isolation, the polarization splitter 10 and the first transition waveguide 40 must be symmetrical and have co-linear axes. In order to ensure that the transmission phases of the two equally divided vertical (or horizontal) polarization signals are identical, all structures between the input of the polarization splitter 10 and the output of the power combiner 30 must be symmetrically arranged about the plane yoz where the central axis is located, and at least one of the central axes of the power combiner 30 is arranged co-linearly with the central axis of the polarization splitter 10. The central axes of the two power combiners 30 may be at any angle between 0 and 90 degrees, and in the embodiment of fig. 1 and 2, this angle is 45 degrees. All of the first waveguide flange 60, rectangular waveguide port 61, through hole 62 and second waveguide flange 70 are sized as waveguide flanges in the national standard code BJ320 standard.

Referring to fig. 11, fig. 11 is a graph of simulated scattering parameters of a polarization splitter 10 of a waveguide quadrature mode converter according to an embodiment of the present invention. The first port is excited by vertical (or horizontal) polarization, the reflection coefficient of the first port of the main waveguide 11 and the reflection coefficient of the second port 15 of the sub waveguide 13 are smaller than-20 dB at 28.8-40GHz, are smaller than-13 dB at Ka full frequency band, and the transmission coefficient curves in any polarization direction show ideal-3-dB equivalent power division response.

Referring to fig. 12, fig. 12 is a graph of simulated scattering parameters of a power combiner 30 of a waveguide quadrature analog-to-digital converter according to an embodiment of the present invention. The reflection coefficient of the three ports of the power combiner 30 is smaller than-22 dB, and the transmission coefficient curve shows ideal-3-dB equivalent power division response.

Referring to fig. 13, fig. 13 is a graph of simulated scattering parameters of a transition waveguide of a waveguide quadrature mode converter according to an embodiment of the present invention, wherein fig. 13 (a) is a graph of simulated scattering parameters of a first transition waveguide 40, and fig. 13 (b) is a graph of simulated scattering parameters of a second transition waveguide 50. The port reflection coefficients of the two transition waveguides are smaller than-20 dB, which shows that the influence of the introduction of the transition waveguides on the transmission performance of the waveguide quadrature mode converter is small.

Referring to fig. 14, fig. 14 is a graph of simulated scattering parameters of an air cavity model of a waveguide quadrature mode converter (without the first transition waveguide 40) according to an embodiment of the present invention. In the Ka full frequency band, in the vertical polarization direction, the port reflection coefficient is smaller than-14 dB, the transmission loss is smaller than 0.1dB, the polarization isolation is larger than 60dB, and the port isolation is larger than 60dB; in the horizontal polarization direction, the port reflection coefficient is smaller than-15 dB, the transmission loss is smaller than 0.1dB, the polarization isolation is larger than 60dB, and the port isolation is larger than 55dB.

In order to verify that the waveguide quadrature analog converter provided by the invention has excellent radio frequency performance, full-wave electromagnetic simulation, processing and radio frequency measurement are carried out on the waveguide quadrature analog converter in the embodiment of the invention. The device adopts photosensitive resin as a structural material and is integrally formed by 3-D printing through a multi-nozzle ink-jet process, and the printing forming direction is the vertical direction shown in figure 2. After printing, all medium supports inside and outside the model can be heated, melted and removed, and the structure of the device is not damaged in the support removing process, so that the integral forming of the model is not limited by the generation positions and the number of the supports. And finally, polishing and cleaning the model, and plating copper on the whole surface of the model to obtain the final device.

Referring to fig. 15 (a) to 15 (d), fig. 15 (a) shows a simulation and measured scattering parameter (S) of a waveguide quadrature converter (including a first transition waveguide 40) in a vertical polarization direction according to an embodiment of the present invention ^V ₁₁ And S is ^V ₂₁ ) FIG. 15 (b) is a graph showing the simulation and measured scattering parameters (S) of a waveguide quadrature mode converter (including a first transition waveguide 40) in the horizontal polarization direction according to an embodiment of the present invention ^H ₁₁ And S is ^H ₃₁ ) Fig. 15 (c) is a graph showing the transmission coefficient S in fig. 15 (a) and 15 (b) ^V ₂₁ And S is ^H ₃₁ FIG. 15 (d) is a schematic representation of a waveguide quadrature mode converter (including a first transition waveguide 40) according to an embodiment of the present invention ^V ₃₁ 、S ^H ₂₁ And S is ₂₃ And a parameter graph representing polarization isolation and port isolation of the device. It can be seen that in the frequency range of 26.5-38GHz, the measured and simulated scattering parameter curves are consistent and identical, the accuracy of simulation results and the reliability of the processing technology are verified, and the excellent radio frequency performance of the waveguide quadrature analog converter is also verified. In the vertical polarization direction, the measured port reflection coefficient is smaller than-10 dB, the measured transmission loss is smaller than 0.75dB, the measured polarization isolation is larger than 30dB, and the measured port isolation is larger than 29dB; in the horizontal polarization direction, the measured port reflection coefficient is less than-10 dB, the measured transmission loss is less than 0.75dB, the measured polarization isolation is more than 28dB, and the measured port isolation is more than 29dB.

The waveguide quadrature mode converter corresponding to the scattering parameter curves simulated in fig. 15 (a) to 15 (d) has the following key dimensions.

(1) Rectangular waveguide port 61: the width of the wide edge is 7.112 mm, and the length of the narrow edge is 3.556 mm;

(2) First transition waveguide 40: the length is 25 mm, and the inner diameter of the circular waveguide is 8.8 mm;

(3) Shaping round table 16: the diameter of flat cylinder 165 is 6.232 mm, the height is 0.546 mm, the bottom surface diameter of flat round table 164 is 6.232 mm, the top surface diameter is 3.262 mm, the height is 0.974 mm, the bottom surface diameter of tall round table 163 is 3.262 mm, the top surface diameter is 1.586 mm, the height is 1.614 mm, the diameter of small cylinder 162 is 1.586 mm, the height is 0.572 mm, and the diameter of hemispherical top surface 161 is 1.586 mm;

(4) Curved waveguide 20: the bending angles of the two bending waveguides 20 are 45 degrees, and the curvature radiuses are 5 mm;

(5) Power combiner 30: the bending angle of the bent waveguide 20 is 45 degrees, the radius of curvature is 4.253 mm, the lengths of the two connecting waveguides 31 in the Y-junction are 6.735 mm, and the length of the combining waveguide 32 in the Y-junction is 3.088 mm;

(6) Second transition waveguide 50: the length is 6 mm, and the major and minor axis lengths of the elliptical port (fourth port) are 7.45 mm and 3.6 mm, respectively.

It should be emphasized again that, first, the waveguide orthogonal mode converter provided by the embodiment of the invention is designed by fusing the process principle of 3-D printing, has a smooth curved surface profile, does not have any abrupt discontinuous structure inside the cavity, can be integrally manufactured and molded, has extremely high compatibility of the structure to the 3-D printing process, and can further mold the first waveguide flange 60 and the second waveguide flange 70 so as to reduce the weight thereof and reduce the use of supporting materials in the molding process; second, the vertical print-forming as shown in fig. 2 can maintain the structural symmetry of the polarization separator 10, and minimize the deterioration of the device isolation due to the deformation of the 3-D print structure.

In the embodiments provided herein, it should be understood that, first, the disclosed shaping design method and exemplary shaping structure may be universally applicable to other types of microwave broadband or narrowband devices. For example, the elliptical waveguide can be widely applied to passive devices such as power splitters, couplers, magic ts, filters and the like; the configuration of the shaping table 16 may be further optimized or the design may be reshaped according to the design requirements of other devices. Secondly, the geometry and the size of the cavity involved in shaping are merely illustrative, and in practical application, the cavity structure used for shaping can be flexibly selected according to radio frequency index, space size, electromagnetic wave mode distribution rule and the like. For example, the structure of the polarization separation cavity 12 may be further optimized, the dimensions of the elliptical waveguide and the transition waveguide may be scaled according to the operating frequency band of the device, and the orientation of the polarized output ports may be tailored according to the application requirements. Thirdly, the disclosed shaping structure is suitable for various nonmetal/metal 3-D printing processes and printing materials, and the universality of the structural design method is strong.

The foregoing description of a waveguide quadrature analog converter is provided by the present invention, and it will be apparent to those skilled in the art from this disclosure that modifications may be made in the specific implementation and application scope of the embodiments of the present invention. In summary, the present description should not be construed as limiting the invention.

Claims

1. The waveguide orthogonal mode converter is characterized by comprising a metal shell, wherein the metal shell comprises a polarization separator, two groups of bent waveguides and two power synthesizers; the two groups of the bent waveguides are respectively connected between the polarization separator and the two power synthesizers, the polarization separator is used for separating two mutually orthogonal linear polarized waves synchronously transmitted in the same waveguide into two paths of equal-amplitude inverted signals in respective polarization directions, the two groups of the bent waveguides are respectively used for transmitting the polarized separated signals to the power synthesizers, and the power synthesizers are used for synthesizing the two paths of equal-amplitude inverted signals in each polarization direction into one path;

the polarization separator comprises a main waveguide, a polarization separation cavity and two groups of waveguides, wherein the main waveguide is communicated with one side of the polarization separation cavity, and the two groups of waveguides are respectively communicated with the other side of the polarization separation cavity; the polarization separation cavity is used for separating two mutually orthogonal linear polarization waves synchronously transmitted in the main waveguide into two paths of signals with equal amplitude and opposite phase in respective polarization directions, and transmitting the signals to the two groups of curved waveguides through the two groups of split waveguides respectively; each group of the sub-waveguides comprises two sub-waveguides; the included angles between the central axes of the four branch waveguides and the central axis of the main waveguide are between 90 degrees and 150 degrees;

the power combiner comprises two connecting waveguides and a combining waveguide, wherein the two connecting waveguides are connected with the combining waveguide in a Y shape; the included angles between the central axes of the two connecting waveguides and the central axis of the combined waveguide are respectively 90-150 degrees; the central axis of at least one power combiner coincides with the central axis of the polarization separator; the included angle between the central axes of the two power synthesizers is between 0 and 90 degrees;

the metal shell is also provided with an inner cavity which respectively penetrates through the polarization separator, the two groups of bent waveguides and the two power synthesizers, and the inner cavity is formed by enclosing smooth and continuous curved surfaces; the cross section of the inner cavity of the metal shell along the transmission direction perpendicular to the linear polarized wave is a first cross section, and in the metal shell, at least the outline of the curved waveguide inner cavity and the outline of the power combiner inner cavity along the first cross section are symmetrical closed curves; the symmetrical closed curves are symmetrical structures along two mutually perpendicular directions of the first section, and the maximum lengths of the symmetrical closed curves along the two mutually perpendicular directions of the first section are different.

2. The waveguide quadrature analog converter of claim 1, wherein each set of said curved waveguides comprises two curved waveguides for transmitting two equal-amplitude inverted signals in each polarization direction, respectively.

3. The waveguide quadrature analog converter of claim 1, wherein said symmetrical closed curve is elliptical.

4. A waveguide quadrature mode converter as claimed in any one of claims 1 to 3 wherein the polarisation separators are axisymmetric in both polarisation directions;

and/or the polarization separator is in a rotationally symmetrical structure.

5. The waveguide quadrature analog converter of claim 4, wherein the central axes of two sets of said split waveguides are perpendicular to each other.

6. The waveguide quadrature analog converter of claim 4, wherein a bottom center of the polarization separation cavity has a shaped circular truncated cone for polarization separation and impedance matching.

7. The waveguide quadrature analog-to-digital converter of claim 6, wherein the shaping circular truncated cone is circular along a second cross section perpendicular to the main waveguide central axis, the shaping circular truncated cone comprises a plurality of circular structures, the plurality of circular structures are stacked successively from bottom to top, the second cross section areas of the plurality of circular structures have a decreasing trend from bottom to top, and at least one of the circular structures located in the middle is circular truncated cone.

8. A waveguide quadrature mode converter as claimed in any one of claims 1 to 3, wherein the power combiner is of symmetrical construction.

9. The waveguide quadrature mode converter of claim 8 wherein the center of the ends of the inner junction of two of said connecting waveguides is formed with a curved notch.

10. A waveguide quadrature mode converter as claimed in claim 2 or claim 3 wherein the end of the polarisation splitter remote from the power combiner and the ends of the two power combiners remote from the polarisation splitter are each provided with a waveguide flange;