A high-power microwave circular waveguide TM01-TE11 mode converter

Abstract

The present invention belongs to the field of high-power microwave technology and discloses a high-power microwave circular waveguide TM01-TE11 mode converter, which is mainly composed of an input circular waveguide, a rectangular waveguide, and an output circular waveguide in cascade. The central axes of the input circular waveguide and the output circular waveguide are in the same position, and the device ports are coaxial. The rectangular waveguide is short-circuited at both ends, and the length of the two short-circuit surfaces from the central axis of the system differs by a quarter of the waveguide wavelength. The waveguide walls where the wide sides are located are respectively provided with an input interface and an output interface, the input interface is connected to the input circular waveguide, and the output interface is connected to the output circular waveguide. In order to reduce the circular waveguide TE11 reflection mode, two metal plates are radially arranged inside the input circular waveguide. The present invention realizes the conversion of the circular waveguide TM01 mode to the circular waveguide TE11 mode, has the advantages of easy processing, compact structure, and coaxial center of the input port and output port, and can be applied to high-power microwave systems.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-power microwaves, and in particular relates to a circular waveguide TM01-TE11 mode converter with easy processing, compact structure, and coaxial input and output ports. Background Art

[0002] High-power microwave technology, a product of the integration of plasma physics and pulsed power technology, emerged in the 1970s. It has applications in advanced communications, high-sensitivity, ultra-long-range radar detection, directed energy applications, and power transmission. However, based on current technology, most high-power microwave applications require high-power microwave systems to radiate energy in a concentrated and directional manner. However, current high-power microwave sources generate microwave modes in circular waveguide TM01 or coaxial TEM. The radiation patterns of these modes exhibit a circular distribution with zero axial gain. Directly driving radiating antennas with these modes results in energy dispersion and high sidelobe levels, hindering the spatial transmission and directional emission of high-power microwave systems. Therefore, before radiating energy, high-power microwave systems require a mode converter to convert the circular waveguide TM01 or coaxial TEM mode into the highly directional, directional circular waveguide TE11 mode.

[0003] Typical mode converters include double-bend and triple-bend structures. This structure is designed based on the theory of mode coupling. By bending the waveguide axis, the various modes in the waveguide are energy-coupled, thereby achieving mode conversion. This type of mode converter has a very high conversion efficiency, which can theoretically reach 99.99%. However, since it involves the processing of curved waveguides, the device processing is relatively difficult; and the centers of the input port and output port of the double-bend structure are not on the same axis, which is not conducive to the overall integration of high-power microwave systems. Although the triple-bend structure solves the problem of the input port and output port centers not being coaxial, the problems of device processing difficulty and non-compact structure are more serious. In order to solve the above problems, the present invention designs a high-power microwave circular waveguide TM01-TE11 mode converter that is easy to process, compact in structure, and has coaxial input and output port centers. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to design a high-power microwave mode converter that is easy to process, compact in structure, and with coaxial input and output ports, so as to realize the conversion from circular waveguide TM01 mode to circular waveguide TE11 mode.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A high-power microwave circular waveguide TM01-TE11 mode converter is characterized by being composed of an input circular waveguide, a rectangular waveguide, and an output circular waveguide connected in cascade; the central axes of the input circular waveguide and the output circular waveguide coincide with each other, and two metal plates are radially arranged inside the input circular waveguide; the two ends of the rectangular waveguide are short-circuited, and the two waveguide walls where the wide side is located are respectively provided with an input interface and an output interface, the input interface being connected to the input circular waveguide, and the output interface being connected to the output circular waveguide.

[0007] Furthermore, the radius of the input circular waveguide is R1, which satisfies the following conditions: Where c is the speed of light and f is the operating frequency of the mode converter.

[0008] Furthermore, the rectangular waveguide has a wide side of W, a narrow side of H2, and a length of L; the length L satisfies the following conditions: where λ TE10 is the guided wavelength of the TE10 mode in the rectangular waveguide.

[0009] Furthermore, the radius of the output circular waveguide is R2, which satisfies the following conditions:

[0010] Furthermore, both ends of the metal plate are connected to the inner wall of the input circular waveguide in an arc shape, the width of the metal plate is D, and the thickness is t; the distance between the two metal plates is H4, and the distance between the first metal plate and the port of the input circular waveguide is H5.

[0011] The mode conversion process of the present invention is as follows: the input circular waveguide is connected to the upstream high-power microwave source device, the circular waveguide TM01 mode is injected, and the circular waveguide TM01 mode is transmitted to the rectangular waveguide to stimulate the formation of a rectangular TE10 mode; the rectangular TE10 mode is reflected to the central axis of the system by the short-circuit surfaces at both ends of the rectangular waveguide. Since the length of the short-circuit surfaces at both ends from the central axis of the system differs by one-quarter of the guided wave wavelength, the rectangular TE10 modes at both ends have a phase difference of 180° after reflection; then, the two rectangular TE10 modes with a phase difference of 180° are respectively synthesized into a circular waveguide TE11 mode in the input circular waveguide and the output circular waveguide; since the goal of the present invention is to convert the input circular waveguide TM01 mode into the output circular waveguide TE11 mode, measures need to be taken to reduce the TE11 mode reflected into the input circular waveguide. The measures taken by the present invention are to insert two metal plates radially into the input circular waveguide.

[0012] The beneficial effects of the present invention are:

[0013] (1) Simple and compact structure. By cascading two circular waveguides and one rectangular waveguide, the present invention can achieve the conversion of the circular waveguide TM01 mode to the circular waveguide TE11 mode, and the structural design is simple. In addition, the axial dimension of the present invention is 2.3 waveguide wavelengths, and the radial dimension is 1.2 waveguide wavelengths. The overall structure is simple, compact, and easy to process and implement.

[0014] (2) High conversion efficiency and wide operating bandwidth. The mode conversion efficiency of the present invention can reach up to 98.4%, and the relative bandwidth with a conversion efficiency greater than 90% is 10.0%, meeting the requirements of high-power microwave systems.

[0015] (3) The centers of the input port and the output port of the present invention are coaxial, which facilitates system integration and further reduces the overall size of the system.

[0016] (4) The present invention can reduce the reflection mode of the mode converter by reasonably designing the size of the two metal plates and the position of their insertion in the input circular waveguide, thereby improving the mode conversion efficiency and the device performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a three-dimensional structural diagram of the high-power microwave mode converter of the present invention.

[0018] Figure 2 It is a front view of the high power microwave mode converter of the present invention.

[0019] Figure 3 1 is a side view of the high power microwave mode converter of the present invention.

[0020] Figure 4 1 is a top view of the high-power microwave mode converter of the present invention.

[0021] Figure 5 It is a conversion efficiency curve diagram of the high-power microwave mode converter of the present invention.

[0022] Figure 6 4 is a reflection coefficient curve diagram of the high power microwave mode converter of the present invention.

[0023] Reference numerals: 1-input circular waveguide, 2, 3-metal plates, 4-rectangular waveguide, 5-output circular waveguide DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. The embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, the present invention designs a high-power microwave circular waveguide TM01-TE11 mode converter, which is mainly composed of an input circular waveguide (1), a rectangular waveguide (4) and an output circular waveguide (5) connected in cascade. The central axes of the input circular waveguide (1) and the output circular waveguide (5) are at the same position, and the device ports are coaxial. The left and right ends of the rectangular waveguide (4) are short-circuited, and the upper and lower waveguide walls where the wide side is located are respectively provided with an input interface and an output interface, the input interface is connected to the input circular waveguide (1), and the output interface is connected to the output circular waveguide (5). In order to reduce the reflection mode, two metal plates (2, 3) are provided radially on the input circular waveguide (1).

[0026] Figure 2 、 Figure 3 as well as Figure 4 They are the main view, side view and top view of the mode converter, and the dimensional parameters of the mode converter are marked.

[0027] In order to ensure that the input circular waveguide (1) can transmit the TM01 mode and cut off the high-order modes above TE21, the input circular waveguide (1) should meet the following conditions: Where c is the speed of light and f is the operating frequency of the mode converter. The operating frequency of the system of the present invention is 3.0 GHz. Therefore, the radius of the input circular waveguide (1) can be designed to be R1 = 4.75 cm. Similarly, in order to suppress high-order modes without affecting the transmission of the circular waveguide TE11 mode, the radius of the output circular waveguide (5) should meet the following conditions: The radius R2 of the output circular waveguide (5) is 3.40 cm; the heights H1 and H3 of the input circular waveguide (1) and the output circular waveguide (5) are 14.30 cm and 5.00 cm respectively.

[0028] The rectangular waveguide (4) has a wide side W = 9.50 cm, a narrow side H2 = 3.52 cm, and an initial value of the length L can be determined according to the conditions It was found that after debugging, L = 12.30 cm.

[0029] In order to reduce the reflected circular waveguide TE11 mode, two metal plates (2, 3) need to be inserted radially into the input circular waveguide (1). The metal plates (2, 3) have a width D = 2.00 cm, a thickness t = 0.30 cm, and a distance H4 = 3.50 cm between the two metal plates (2, 3). The distance H5 between the first metal plate (2) and the device input port is 5.30 cm.

[0030] Figure 5This is a graph showing the conversion efficiency of the high-power microwave mode converter of the present invention. As shown, the maximum conversion efficiency of the mode converter of the present invention reaches 98.4%. The frequency range in which the conversion efficiency exceeds 90% is between 2.79 GHz and 3.09 GHz (300 MHz), corresponding to a relative bandwidth of 10.0%. This demonstrates that the mode converter has high conversion efficiency and is capable of operating over a wide frequency band.

[0031] Figure 6 This is a reflection coefficient curve for the high-power microwave mode converter of the present invention. As shown, the reflection coefficient of the mode converter at 3.0 GHz is -26 dB; the frequency range where the reflection coefficient is less than -10 dB is 2.78 GHz to 3.10 GHz. These results demonstrate that the designed mode converter exhibits minimal reflection within the operating frequency band and achieves excellent matching at the 3.0 GHz operating frequency.

[0032] In summary, the high-power microwave mode converter of the present invention has the advantages of easy processing, compact structure, and coaxial input and output ports, and can be applied to high-power microwave systems.

Claims

1. A high-power microwave circular waveguide TM01-TE11 mode converter, characterized by: The invention consists of an input circular waveguide, a rectangular waveguide and an output circular waveguide connected in cascade; the central axes of the input circular waveguide and the output circular waveguide coincide with each other, and two metal plates are radially arranged inside the input circular waveguide; the two ends of the rectangular waveguide are short-circuited, and the two waveguide walls where the wide side is located are respectively provided with an input interface and an output interface, the input interface is connected to the input circular waveguide, and the output interface is connected to the output circular waveguide.

2. The high-power microwave circular waveguide TM01-TE11 mode converter according to claim 1, characterized in that: The radius of the input circular waveguide is R1, which satisfies the following conditions: ,in c is the speed of light, f is the operating frequency of the mode converter.

3. The high-power microwave circular waveguide TM01-TE11 mode converter according to claim 1, characterized in that: The rectangular waveguide has a wide side of W, a narrow side of H2, and a length of L. The length L satisfies the following conditions: , where λ TE10 is the guided wavelength of the TE10 mode in the rectangular waveguide.

4. The high-power microwave circular waveguide TM01-TE11 mode converter according to claim 1, characterized in that: The radius of the output circular waveguide is R2, which satisfies the following conditions: .

5. The high-power microwave circular waveguide TM01-TE11 mode converter according to claim 1, characterized in that: The two ends of the metal plate are connected to the inner wall of the input circular waveguide in an arc shape.

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