A design method of a TE01 and TM11 circular waveguide dual-mode filter

Abstract

A design method of a TE01 and TM11 circular waveguide dual-mode filter, the filter comprising two hollow circular cavities, an input coupling cutoff waveguide, an output coupling cutoff waveguide, a coupling cutoff waveguide, a cavity, and a cover plate, the two hollow circular cavities being connected to the input coupling cutoff waveguide and the output coupling cutoff waveguide respectively, the coupling cutoff waveguide being connected to the two hollow circular cavities, the cavity being provided with a recess corresponding in shape and size to the two hollow circular cavities, the input coupling cutoff waveguide, the output coupling cutoff waveguide, and the coupling cutoff waveguide after being connected for embedding, and the cover plate being fixed on the cavity by screws to form a seal.

Description

Technical Field

[0001] This invention belongs to the field of microwave technology, specifically relating to a filter technology. Background Technology

[0002] In the fields of communication satellites and aerospace, cavity filters are very important passive devices, such as TE102, TE201, TE301 rectangular waveguide dual-mode, and the traditional TE11p circular waveguide dual-mode.

[0003] The TE102 and TE201 rectangular waveguide dual-mode filters cannot have their cavities aligned in a straight line. Although the TE01 solves the problem of the cavities not being aligned in a straight line, its input and output coupling cutoff waveguides are too thin, making them impossible to fabricate in engineering, and its dual-mode size is large.

[0004] The TE11p circular waveguide dual-mode filter can only achieve symmetrical transmission zeros. The input / output coupling diaphragms and the intermediate coupling diaphragm are too thin, requiring wire cutting for the cross-shaped holes on the diaphragms, making manufacturing complex. The entire filter needs to be manufactured in sections, requiring many fastening screws for assembly, resulting in low assembly accuracy. Screws cannot be added to the diaphragms, making debugging time-consuming and producing poor waveforms. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, this invention proposes a design method for a circular waveguide dual-mode filter using TE01 and TM11. To achieve the above objective, this invention adopts the following technical solution.

[0006] The filter includes two hollow circular cavities, an input coupling cutoff waveguide, an output coupling cutoff waveguide, a coupling cutoff waveguide, a cavity, and a cover plate. The two hollow circular cavities are respectively connected to the input coupling cutoff waveguide and the output coupling cutoff waveguide. The coupling cutoff waveguide connects the two hollow circular cavities. The cavity is provided with grooves, the shape and size of which correspond to the two hollow circular cavities, the input coupling cutoff waveguide, the output coupling cutoff waveguide, and the coupling cutoff waveguide after connection, for embedding. The cover plate is fixed to the cavity with screws to form a seal.

[0007] By changing the diameter of the two hollow cavities, the TE01 and TM11 modes can resonate simultaneously at the required center frequency.

[0008] By changing the aspect ratio of the two hollow circular cavities, the cavities are transformed into elliptical cavities, creating perturbations that separate the TE01 and TM11 modes, generating a coupling relationship and forming the coupling bandwidth required for filter design. This causes the non-resonant modes of the two hollow circular cavities to generate transmission zeros.

[0009] Adjust the width, length, and offset from the center of the two hollow cavities of the input and output coupling cutoff waveguides to meet the input and output bandwidth requirements of the filter design.

[0010] Adjust the width, length, and offset from the center of the two hollow cavities of the coupling cutoff waveguide to meet the coupling bandwidth required for the filter design.

[0011] In 3D electromagnetic field simulation software HFSS or CST, perform overall modeling and simulation, repeating the above steps multiple times until the filter bandwidth, out-of-band rejection, and return loss meet the design requirements.

[0012] The beneficial effects of this invention are:

[0013] This filter has high power, high Q value, low loss, and freely controllable transmission zero position. It is suitable for large-scale production, can be applied to practical engineering, and meets the increasing application requirements of current communication systems.

[0014] Since the Z-axis direction of the TE01 and TM11 circular waveguide dual-mode filters is unrestricted, the unloaded quality factor Q of the cavity can be increased and the insertion loss of the filter can be reduced by increasing the height of the circular waveguide in the Z-axis direction, and the mode inside the filter will not be changed as a result.

[0015] The TE102 and TE301 rectangular waveguide dual-mode filters can overcome the problem that the cavities of the TE102 and TE201 rectangular waveguide dual-mode filters are not on a straight line. They can be machined in one piece on a CNC milling machine, reducing assembly errors. If the machining accuracy is controlled within a certain range, the debugging process can be eliminated, enabling large-scale production.

[0016] The TE01 and TM11 circular waveguide dual-mode filters are a new type of dual-mode filter. They can control the position of the transmission zero point by changing the ratio of the circular diameter. They are suitable for cavity filters in communication satellites and aerospace fields, and have outstanding advantages both domestically and internationally. Attached Figure Description

[0017] Figure 1 It is a disassembled structural diagram. Figure 2 It is a simulation waveform diagram.

[0018] Reference numerals: 1-cavity, 2-coupled cutoff waveguide, 3-input coupled cutoff waveguide, 4 and 5-hollow circular cavity, 6-output coupled cutoff waveguide, 7-cover plate. Detailed Implementation

[0019] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] The structure of the filter is as follows Figure 1 As shown, hollow circular cavity 4 is connected to input coupling cutoff waveguide 3, hollow circular cavity 5 is connected to output coupling cutoff waveguide 6, and coupling cutoff waveguide 2 connects two hollow circular cavities 4 and 5. Cavity 1 is provided with grooves whose shape and size correspond to the connected hollow circular cavities 4 and 5, input coupling cutoff waveguide 3, output coupling cutoff waveguide 6, and coupling cutoff waveguide 2, for them to be embedded. Cover plate 7 is fixed to the cavity with screws to form a seal.

[0021] The installed filter is equivalent to a fourth-order generalized Chebyshev filter with a pair of transmission zeros. The synthesis of its coupling matrix is ​​the same as that of a typical generalized Chebyshev filter. The simulation waveform is as follows: Figure 2 As shown, the center frequency of the HFSS simulated filter is 14.977 GHz, the bandwidth is 112 MHz, the out-of-band rejection is 14.613 GHz, the rejection is greater than 60 dB, and the return loss is greater than 19 dB.

[0022] The above are embodiments of the present invention and do not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention are included within the protection scope of the present invention.

Claims

1. A design method for a circular waveguide dual-mode filter using TE01 and TM11, characterized in that, include: Two hollow circular cavities, one input coupling cutoff waveguide, one output coupling cutoff waveguide, one coupling cutoff waveguide, one cavity, and one cover plate; Two hollow circular cavities are connected to the input coupling cutoff waveguide and the output coupling cutoff waveguide, respectively. The coupling cutoff waveguide connects the two hollow circular cavities. The cavity is provided with grooves, the shape and size of which correspond to the two hollow circular cavities, the input coupling cutoff waveguide, the output coupling cutoff waveguide, and the coupling cutoff waveguide, for embedding. The cover plate is fixed to the cavity with screws to form a seal. By changing the diameter of the two hollow circular cavities, the TE01 and TM11 modes can resonate simultaneously at the required center frequency. By changing the aspect ratio of the two hollow circular cavities, the cavities are transformed into elliptical cavities, forming a perturbation that separates the TE01 and TM11 modes, creating a coupling relationship and forming the coupling bandwidth required for the filter design. This causes the non-resonant modes of the two hollow circular cavities to generate transmission zeros. The width, length, and offset from the center of the two hollow circular cavities of the input and output coupling cutoff waveguides are adjusted to meet the input and output bandwidth required for the filter design. Adjust the width, length, and offset from the center of the two hollow circular cavities of the coupling cutoff waveguide to meet the coupling bandwidth required for the filter design. Perform overall modeling and simulation in 3D electromagnetic field simulation software HFSS or CST, and repeat the adjustments multiple times until the filter bandwidth, out-of-band suppression, and return loss meet the design requirements.

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