A waveguide TE10 to circular polarized TE21 mode converter

Abstract

The application discloses a waveguide TE10-to-circular polarization TE21 mode converter and belongs to the technical field of millimeter wave and terahertz devices, which comprises an input channel, an isolation channel and an output channel; the input channel comprises a rectangular waveguide with one E-plane cut corner and an over-mode rectangular waveguide with two symmetrical H-plane cut corners, which are vertically crossed; the isolation channel is the same in structure as the input channel, and both are symmetrically arranged in parallel; the output channel comprises a rectangular-to-circular conversion waveguide, a stepped partition and an over-mode circular waveguide; the stepped partition is located inside the rectangular-to-circular conversion waveguide and the over-mode circular waveguide, and the bottom of the stepped partition is attached to the bottom of the two waveguides. The application realizes the conversion of TE10 mode-TE20 mode-circular polarization TE21 mode through a simple and compact structure, and can realize double circular polarization TE21 mode; compared with the existing structure, the application has the advantages of simple and compact structure, easy design, wide bandwidth, low loss and high amplitude and phase consistency, and has greater application value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of millimeter wave and terahertz devices, and particularly relates to a waveguide TE10-to-circularly polarized TE21 mode converter. BACKGROUND

[0002] The circular waveguide TE21 mode is widely used in the antenna feed of the single-pulse automatic tracking ground station and the high-power vacuum electron device. At present, the method for exciting the circular waveguide linearly polarized TE21 mode mainly uses four E-plane waveguide branches to excite in the circular waveguide, and the signal amplitudes of the four excitation arms are equal, and the phase difference of adjacent branches is 180°. This method can obtain a relatively wide working bandwidth, but since a power divider is needed to obtain four signals meeting the excitation conditions, the overall volume of the device is large, the waveguide path is long, and the high-frequency loss is high.

[0003] At present, there are two methods to obtain the circularly polarized TE21 mode. One method (such as the Chinese patent with the publication number CN 117878553 A) is to increase the excitation branches from four to eight to realize the excitation of two polarized degenerate circular waveguide linearly polarized TE21 modes at the same time, and obtain the circularly polarized TE21 mode, however, the structure realized based on this method is too complex, and the practicability is poor. The other method (such as the literature "Design of a TE 11 -TE 21 Mode ConverterBased on a Three-fold Helically Corrugated Waveguide" published by Junqiang Gao et al.) is to first convert the TE10 mode into the circularly polarized TE11 mode, and then use the helical corrugated waveguide following a specific function to obtain the circularly polarized TE21 mode within a narrow band, since the working bandwidth of the helical corrugated waveguide is narrow, and the waveguide path is long, the design of this circularly polarized TE21 mode is also relatively complex. SUMMARY

[0004] In view of the problem of complex structure existing in the existing methods for obtaining the circularly polarized TE21 mode, the application provides a waveguide TE10-to-circularly polarized TE21 mode converter, which has the advantages of simple and compact structure, wide bandwidth, low loss and high amplitude and phase consistency.

[0005] The technical scheme adopted by the application is as follows:

[0006] A waveguide TE10-to-circularly polarized TE21 mode converter, comprising an input channel, an isolation channel and an output channel.

[0007] The input channel includes a rectangular waveguide having an E-plane cut corner and an over-moded rectangular waveguide having two symmetrical H-plane cut corners; wherein the rectangular waveguide and the over-moded rectangular waveguide are arranged perpendicularly and crosswise, and the E-plane of the rectangular waveguide on one side with no cut corners is coplanar with the H-plane on one side of the over-moded rectangular waveguide, so that the input channel is symmetrical about the center of the E-plane of the rectangular waveguide; the uncut rectangular port of the rectangular waveguide is used as the input port, and the uncut rectangular port of the over-moded rectangular waveguide is connected to the starting end of the output channel;

[0008] The isolation channel has the same structure as the input channel, and the two are arranged in parallel and symmetrically. The uncut rectangular port of the rectangular waveguide in the isolation channel is used as the isolation port, and the uncut rectangular port of the over-moded rectangular waveguide is connected to the starting end of the output channel.

[0009] The output channel includes a rectangular-circular conversion waveguide, a stepped partition, and an over-moded circular waveguide; wherein the end of the rectangular-circular conversion waveguide is connected to the beginning of the over-moded circular waveguide; the stepped partition is located inside the rectangular-circular conversion waveguide and the over-moded circular waveguide, and its bottom is in contact with the bottoms of the rectangular-circular conversion waveguide and the over-moded circular waveguide; the beginning of the rectangular-circular conversion waveguide is divided into two rectangular ports by the stepped partition, which are respectively connected to the input channel and the isolation channel; the end of the over-moded circular waveguide is the output port; the height of the stepped partition decreases in steps from the beginning of the rectangular-circular conversion waveguide to the inside of the over-moded circular waveguide, and the top of the first step is in contact with the top of the rectangular-circular conversion waveguide.

[0010] Furthermore, the length-to-width ratio of the waveguide opening of the rectangular waveguide is 2:1, and the length-to-width ratio of the waveguide opening of the over-moded rectangular waveguide is 4:1.

[0011] Furthermore, the length and height of the E-plane cut angle of the rectangular waveguide and the H-plane cut angle of the over-moded rectangular waveguide are equal, the length is 1.3 to 1.6 times the wavelength, and the height is 0.4 to 0.6 times the wavelength.

[0012] Furthermore, the length of the rectangular-circular conversion waveguide is 1 to 1.5 times the wavelength.

[0013] Furthermore, the thickness of the stepped partition is 0.075 to 0.15 times the wavelength, including at least 4 steps, and is used to achieve mode conversion from the rectangular waveguide TE20 mode to the circularly polarized TE21 mode in the circular waveguide.

[0014] Furthermore, the first-step length of the stepped baffle is 0.5 to 0.8 times the length of the rectangular-circular conversion waveguide. The first-step length of the stepped baffle is required to be smaller than the length of the rectangular-circular conversion waveguide, which can reduce the impact of the increase in the TE20 mode cutoff frequency due to the reduction in waveguide size, and help improve the low-frequency mode conversion effect.

[0015] Further, when the stepped septum includes 6 steps, the length of each step is 0.88, 0.09, 0.21, 0.32, 0.41 and 0.29 times of the wavelength in turn, and the height difference between adjacent steps is less than 0.25 times of the wavelength except the first step. The above-mentioned size is only one set of optimal solution, and other optimal solutions exist.

[0016] Further, the overmoded rectangular waveguide is a narrow edge gradual change structure, and the narrow edge of the H-plane cut corner end to the uncut corner rectangular port gradually increases.

[0017] Further, the overmoded rectangular waveguide adopts a stepped gradual change structure or a smooth gradual change structure.

[0018] Further, the overmoded rectangular waveguide includes 3-5 waveguide steps, the height of the waveguide step start end is half of the height of the overmoded rectangular waveguide, and the length of each waveguide step is 0.25 times of the wavelength except the waveguide step start end.

[0019] Further, the radius R of the overmoded circular waveguide satisfies:

[0020]

[0021] wherein, λ c1 is the cutoff wavelength of the TM 01 mode; and λ c2 is the cutoff wavelength of the TE 01 mode.

[0022] Further, the isolation port is externally connected with a matching load.

[0023] The working principle of the waveguide TE10 to circular polarization TE21 mode converter is as follows:

[0024] When the TE10 mode signal is input from the input port, the signal transmission is through the E-plane cut corner, the height of the rectangular waveguide gradually decreases, the transmission condition of the TE10 mode is broken, and the TE10 mode is forced to change to other modes; the H-plane cut corner of the overmoded rectangular waveguide provides the condition for the conversion of the TE10 mode to the TE20 mode, and then the rectangular waveguide TE20 mode is output at the input channel end (i.e. the uncut corner rectangular port of the overmoded rectangular waveguide); the overall structure is simple and symmetrical, so that the mode conversion purity is high; the overmoded rectangular waveguide is designed as a narrow edge gradual change structure, which is helpful to realize high-efficiency and wide-band mode conversion.

[0025] Since the rectangular waveguide TE20 mode output at the end of the input channel is linearly polarized wave, according to the basic principle of electromagnetic field, any linearly polarized wave can be vectorially decomposed into two orthogonal components, so in the output channel, the rectangular waveguide TE20 mode will be converted into the circular waveguide TE21 mode; the asymmetric stepped partition in the output channel realizes the function of vectorial decomposition, and makes the two orthogonal TE21 modes produce a phase difference of 90°, thereby generating the circularly polarized TE21 mode in the circular waveguide.

[0026] Further, when the TE10 mode signal is inputted from the input port alone, the waveguide TE10 to circularly polarized TE21 mode converter outputs the left-handed circularly polarized TE21 mode; when the TE10 mode signal is inputted from the isolation port alone, the waveguide TE10 to circularly polarized TE21 mode converter outputs the right-handed circularly polarized TE21 mode; and further realizes the dual circularly polarized TE21 mode.

[0027] The waveguide TE10 to circularly polarized TE21 mode converter has the advantages that:

[0028] The waveguide TE10 to circularly polarized TE21 mode converter has the advantages that: BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A three-dimensional view of the waveguide TE10 to circularly polarized TE21 mode converter provided for the embodiment 1 of the present application;

[0030] Figure 2 A three-dimensional view of the input channel in the waveguide TE10 to circularly polarized TE21 mode converter provided for the embodiment 1 of the present application;

[0031] Figure 3 A three-dimensional perspective view of the output channel in the waveguide TE10 to circularly polarized TE21 mode converter provided for the embodiment 1 of the present application;

[0032] Figure 4 A simulation result graph of the S parameter of the waveguide TE10 to circularly polarized TE21 mode converter provided for the embodiment 1 of the present application applied to the frequency band of 410-490GHz;

[0033] Figure 5 Simulation results of the amplitude difference, phase difference and axial ratio of the waveguide TE10 to circularly polarized TE21 mode converter provided for the embodiment 1 of the present application applied to the frequency band of 410-490GHz;

[0034] The explanation of each mark in the drawing is as follows:

[0035] 01: input port; 02: isolation port; 03: output port; 1: input channel; 2: isolation channel; 3: output channel; 11: rectangular waveguide; 12: E-plane corner cut; 13: H-plane corner cut; 14: stepped gradual change structure; 15: overmoded rectangular waveguide; 32: rectangular-circular conversion waveguide; 33: overmoded circular waveguide; 34: stepped partition. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0038] Embodiment 1

[0039] The embodiment provides a waveguide TE10-to-circularly polarized TE21 mode converter working in a 410-490 GHz frequency band, and the overall three-dimensional structure is as shown in Figure 1 The waveguide TE10-to-circularly polarized TE21 mode converter includes an input channel 1, an isolation channel 2 and an output channel 3.

[0040] The isolation channel 2 has the same structure as the input channel 1, and the two are symmetrically arranged in parallel.

[0041] As shown in Figure 2As shown, the input channel 1 includes a rectangular waveguide 11 with an E-plane cut corner 12, and an overmoded rectangular waveguide 15 with two symmetrical H-plane cut corners 13; wherein the rectangular waveguide 11 is of WR-1.9 type, with a size of 0.483mm*0.241mm; the overmoded rectangular waveguide 15 has a size of 0.966mm*0.241mm; the rectangular waveguide 11 and the overmoded rectangular waveguide 15 are arranged perpendicularly, and the uncut corner side E-plane of the rectangular waveguide 11 is coplanar with one side H-plane of the overmoded rectangular waveguide 15, so that the input channel 1 is centrosymmetric about the E-plane center of the rectangular waveguide 11; the uncut corner rectangular port of the rectangular waveguide 11 is taken as the input port 01, and the uncut corner rectangular port of the overmoded rectangular waveguide 15 is connected with the start end of the output channel 3; the length and height of the E-plane cut corner 12 of the rectangular waveguide 11 and the H-plane cut corner 13 of the overmoded rectangular waveguide 15 are equal, and the specific length is 0.942mm and the height is 0.3mm.

[0042] The overmoded rectangular waveguide 15 is of a narrow-edge gradual change structure, specifically, one side H-plane of the overmoded rectangular waveguide 15 facing the isolation channel 2 is of a planar structure, and the other side H-plane is of a stepped gradual change structure 14.

[0043] The stepped gradual change structure 14 includes four waveguide steps, and the narrow edge from the cut corner end to the uncut corner rectangular port gradually increases; wherein the start end height of the waveguide step is half of the height of the overmoded rectangular waveguide 15, i.e. 0.12mm, and the start end length is 0.575mm; the lengths of the following three waveguide steps are all 0.186mm, and the step heights are 0.138mm, 0.173mm and 0.22mm in sequence.

[0044] In the isolation channel 2, the uncut corner rectangular port of the rectangular waveguide 11 is taken as the isolation port 02, and a matching load is circumscribed outside the isolation port; the uncut corner rectangular port of the overmoded rectangular waveguide 15 is connected with the start end of the output channel 3.

[0045] As Figure 3As shown, the output channel 3 comprises a rectangular-circular conversion waveguide 32, a stepped partition 34 and an overmoded circular waveguide 33; wherein the end of the rectangular-circular conversion waveguide 32 is connected with the start of the overmoded circular waveguide 33; the length of the rectangular-circular conversion waveguide 32 is 0.804 mm; the radius of the overmoded circular waveguide 33 is 0.38 mm; the stepped partition 34 is located inside the rectangular-circular conversion waveguide 32 and the overmoded circular waveguide 33, and the bottom of the stepped partition 34 is attached to the bottom of the rectangular-circular conversion waveguide 32 and the overmoded circular waveguide 33; the start of the rectangular-circular conversion waveguide 32 is divided into two rectangular ports by the stepped partition 34, and the two rectangular ports are connected with the input channel 1 and the isolation channel 2 respectively; the end of the overmoded circular waveguide 33 is the output port 03; the stepped partition 34 comprises 6 steps from the rectangular-circular conversion waveguide 32, and the thickness of the stepped partition 34 is 0.07 mm; the length of each step is 0.58 mm, 0.062 mm, 0.14 mm, 0.215 mm, 0.276 mm and 0.195 mm in sequence, and the height of each step is 0.966 mm, 0.404 mm, 0.264 mm, 0.154 mm, 0.086 mm and 0.01 mm in sequence, wherein the top of the first step is attached to the top of the rectangular-circular conversion waveguide 32.

[0046] It is calculated that the wavelength at 450 GHz is about 0.67 mm, and thus the length of the whole mode converter is only 4.3 times the wavelength.

[0047] The working principle of the waveguide TE10-to-circularly polarized TE21 mode converter is as follows:

[0048] When a TE10 mode signal is input from the input port, the height of the rectangular waveguide gradually decreases when the signal is transmitted through the E-plane cut angle, the transmission condition of the TE10 mode is broken, and the TE10 mode is forced to transform into other modes; the H-plane cut angle of the overmoded rectangular waveguide provides a condition for the conversion of the TE10 mode into the TE20 mode, and then the rectangular waveguide TE20 mode is output from the end of the input channel (i.e. the uncut rectangular port of the overmoded rectangular waveguide); the overall structure is simple and symmetrical, so that the mode conversion purity is high; the overmoded rectangular waveguide is designed as a narrow-edge gradual change structure, which is helpful to realize high-efficiency and wide-band mode conversion.

[0049] Since the rectangular waveguide TE20 mode output from the end of the input channel is a linearly polarized wave, according to the basic principle of electromagnetic field, any linearly polarized wave can be vectorially decomposed into two orthogonal components, so that in the output channel, the rectangular waveguide TE20 mode will be converted into the circular waveguide TE21 mode; the asymmetric stepped partition in the output channel realizes the function of vectorial decomposition, and makes the two orthogonal TE21 modes produce a phase difference of 90°, so as to generate the circularly polarized TE21 mode in the circular waveguide.

[0050] Further, when the TE10 mode signal is inputted from the input port alone, the waveguide TE10 to circular polarization TE21 mode converter outputs left-handed circular polarization TE21 mode; when the TE10 mode signal is inputted from the isolation port alone, the waveguide TE10 to circular polarization TE21 mode converter outputs right-handed circular polarization TE21 mode; and then the dual circular polarization TE21 mode is realized.

[0051] The embodiment adopts three-dimensional electromagnetic simulation software to accurately design the size of the waveguide TE10 to circular polarization TE21 mode converter, and applies it to the 410-490GHz frequency band for simulation, and the simulation results are as shown in Figure 4 and Figure 5 The simulation results show that in the 410-490GHz frequency band, the working bandwidth is 17.8%, the input return loss is greater than 15dB, the input isolation is greater than 19dB, the amplitude difference of the TE21 orthogonal mode is less than 0.25dB, the phase difference is 90±13°, and the calculated circular polarization TE21 mode axial ratio is less than 0.25dB.

[0052] In summary, the waveguide TE10 to circular polarization TE21 mode converter has the advantages of simple and compact structure, high consistency of orthogonal mode amplitude, low loss, and wideband operation.

[0053] The above embodiments only illustrate the principles and advantages of the present application, and are not used to limit the present application, and the protection scope of the present application is not limited to the above configurations and embodiments, and those skilled in the art can make other various specific modifications and combinations without departing from the essence of the present application according to the disclosed technology, but still within the protection scope of the present application.

Claims

1. A waveguide TE10 to circularly polarized TE21 mode converter, characterized in that: Including input channel, isolation channel and output channel; The input channel includes a rectangular waveguide having an E-plane cut corner and an over-moded rectangular waveguide having two symmetrical H-plane cut corners; wherein the rectangular waveguide and the over-moded rectangular waveguide are arranged perpendicularly and crosswise, and the E-plane of the rectangular waveguide on one side with no cut corners is coplanar with the H-plane on one side of the over-moded rectangular waveguide, so that the input channel is symmetrical about the center of the E-plane of the rectangular waveguide; the uncut rectangular port of the rectangular waveguide is used as the input port, and the uncut rectangular port of the over-moded rectangular waveguide is connected to the starting end of the output channel; The isolation channel has the same structure as the input channel, and the two are arranged in parallel and symmetrically. The uncut rectangular port of the rectangular waveguide in the isolation channel is used as the isolation port, and the uncut rectangular port of the over-moded rectangular waveguide is connected to the starting end of the output channel. The output channel includes a rectangular-circular conversion waveguide, a stepped partition, and an over-moded circular waveguide; wherein the end of the rectangular-circular conversion waveguide is connected to the beginning of the over-moded circular waveguide; the stepped partition is located inside the rectangular-circular conversion waveguide and the over-moded circular waveguide, with its bottom abutting against the bottoms of both; the beginning of the rectangular-circular conversion waveguide is divided into two rectangular ports by the stepped partition, which are respectively connected to the input channel and the isolation channel; the end of the over-moded circular waveguide is the output port; the height of the stepped partition decreases in steps from the beginning of the rectangular-circular conversion waveguide to the inside of the over-moded circular waveguide, with the top of the first step abutting against the top of the rectangular-circular conversion waveguide.

2. The waveguide TE10 to circularly polarized TE21 mode converter according to claim 1, characterized in that: The length-to-width ratio of the waveguide opening of the rectangular waveguide is 2:1, and the length-to-width ratio of the waveguide opening of the over-moded rectangular waveguide is 4:

1.

3. The waveguide TE10 to circularly polarized TE21 mode converter according to claim 2, characterized in that: The length and height of the E-plane cut angle of the rectangular waveguide are equal to those of the H-plane cut angle of the over-moded rectangular waveguide, the length is 1.3 to 1.6 times the wavelength, and the height is 0.4 to 0.6 times the wavelength.

4. The waveguide TE10 to circularly polarized TE21 mode converter according to claim 2, characterized in that: The length of the rectangular-circular conversion waveguide is 1 to 1.5 times the wavelength.

5. The waveguide TE10 to circularly polarized TE21 mode converter according to claim 2, characterized in that: The thickness of the stepped partition is 0.075 to 0.15 times the wavelength and includes at least 4 steps.

6. The waveguide TE10 to circularly polarized TE21 mode converter according to claim 2, characterized in that: The length of the first step of the stepped partition is 0.5 to 0.8 times the length of the rectangular-circular conversion waveguide.

7. The waveguide TE10 to circularly polarized TE21 mode converter according to claim 2, characterized in that: The over-moded rectangular waveguide has a narrow-side gradient structure, and the narrow side gradually increases from the H-surface corner-cut end to the uncornered rectangular end.

8. The waveguide TE10 to circularly polarized TE21 mode converter according to claim 7, characterized in that: The over-moded rectangular waveguide adopts a stepped gradient structure or a smooth gradient structure.

9. The waveguide TE10 to circularly polarized TE21 mode converter according to claim 2, characterized in that: The over-moded rectangular waveguide includes 3 to 5 waveguide steps. The height of the starting end of the waveguide step is half the height of the over-moded rectangular waveguide. Except for the starting end of the waveguide step, the length of each waveguide step is 0.25 times the wavelength.

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