A high-order mode suppression transition structure based on two-path equal-power excitation of odd-symmetry electric field

Abstract

This invention belongs to the field of microwave technology, specifically providing a high-order mode suppression transition structure based on two equal-power excitation odd-symmetric electric fields to achieve single-mode transition between a rectangular single-mode waveguide and a rectangular overmode waveguide. It includes a rectangular waveguide power divider, a rectangular connecting waveguide, and a rectangular overmode waveguide. The two rectangular connecting waveguides connect the outputs of the two equal-power-dividing rectangular waveguide power dividers to the rectangular overmode waveguide, with their wide-side centers located at 1 / 3 and 2 / 3 of the wide side of the rectangular overmode waveguide, respectively. The rectangular overmode waveguide TE is in-phase excited. 30 At the odd-symmetric location of the mode electric field, the TE in the rectangular overmode waveguide is realized. 30 and TE k0 Suppression of modulo (k is an even number greater than or equal to 2). Its advantage is that it solves the problem of traditional transition mode (TE) not being effectively suppressed. 30 The problem of the module, while realizing the TE k0 Suppression of modulo (k is an even number greater than or equal to 2) has the advantages of good performance, low cost, small size, light weight and easy implementation, and has extremely high application value.

Description

Technical Field

[0001] This invention relates to the field of microwave technology, and more specifically to a high-order mode suppression transition structure. Background Technology

[0002] With the rapid development of fields such as radar and satellite communications, the power requirements for microwave radio frequency signals are increasing. Rectangular waveguides, as commonly used transmission lines for microwave radio frequency signals, have the advantages of low insertion loss and high power capacity, and are therefore widely used.

[0003] As a single-conductor structure, a rectangular waveguide can contain an infinite number of possible field modes, specifically TE. mn Model or TM mn The modulus, where m and n are non-negative integers, and for the TE modulus they cannot both be zero, while for the TM modulus they cannot be zero. The field distribution in the longitudinal direction is a traveling wave with simple harmonic variation. In the transverse direction, since the waveguide is short-circuited at both ends, the wave forms a standing wave. m and n represent the number of m and n half-standing waves distributed on the wide and narrow sides of the waveguide, respectively, and the fields on either side of the field zero are opposite. For example, TE... 10 The electric field distribution of the mode is characterized by a half-standing wave on the wide side, TE 20 The electric field distribution of the mode is characterized by two half-standing waves on the wide side, such as... Figure 1 As shown, TE is also given. 30 and TE 40 The electric field outside the waveguide represents the field inside the waveguide, which is opposite in direction to the electric field inside the waveguide shown in the figure; the field strengths of the same mode are opposite around zero, and the amplitudes of each half-standing wave are equal.

[0004] In a rectangular waveguide, different modes have different cutoff wavelengths, which can be determined by...

[0005]

[0006] Calculations show that the cutoff wavelength is related to the wide side dimension 'a' and the narrow side dimension 'b' of the waveguide, while TE... 10 TE 20 TE 30 The cutoff wavelengths are 2a, a, and 2a / 3, respectively. For each mode, when the operating wavelength... When the operating wavelength is [not specified], this mode can transmit, and is called the transmission mode; when the operating wavelength is [not specified], [the mode can transmit]. When the field is attenuated in a rectangular waveguide, this mode cannot be transmitted and is called the cutoff mode.

[0007] In microwave waveguide applications, overmode waveguides are often used to further reduce transmission loss and increase transmission power. An overmode waveguide is an oversized waveguide capable of transmitting multiple modes simultaneously. Furthermore, overmode waveguides provide more physical space for applications such as waveguide power combining, which is beneficial for fabrication; more physical space often also means better heat dissipation characteristics. However, overmode waveguides also have the disadvantage of easily exhibiting complex field distributions and exciting and transmitting higher-order modes. Therefore, during port excitation, a higher-order mode suppression transition is needed to suppress unwanted modes.

[0008] A higher-order mode suppression transition (PDS) is a passive microwave component used in microwave and millimeter-wave systems. It is used to excite only the dominant mode and suppress other unwanted or difficult-to-use higher-order modes when connecting two different transmission lines. For example, in overmode waveguide applications, higher-order modes can cause energy attenuation of the dominant mode and degrade waveguide performance. Since ports in practical applications are typically of standard waveguide size, a DPS is needed to excite only the required modes in the overmode waveguide when connecting a standard waveguide to an overmode waveguide. Furthermore, when testing overmode waveguide components such as harmonic filters using a vector network analyzer, the excited higher-order modes will also affect the test results if a DPS is not used.

[0009] To achieve good suppression of higher-order modes in a rectangular overmode waveguide and ensure the normal operation of the overmode component, Guo Qian disclosed a wedge-shaped transition waveguide (Guo Qian, Research on Miniaturized Wide-Stopband Waveguide Filters, Sichuan: University of Electronic Science and Technology of China, 2020). This waveguide uses a relatively long linear wedge-shaped transition waveguide to suppress TE signals. 30 Suppression of higher-order modes. The principle is to reduce discontinuities and thus reduce the excitation of higher-order modes through a wedge-shaped gradient structure. Theoretically, it cannot completely suppress higher-order modes, but only controls the energy of higher-order modes within a small range; the higher the suppression of higher-order modes, the longer the wedge structure, especially at low operating frequencies, the wedge structure is very long, greatly increasing the processing difficulty and cost, making it difficult to apply in practice. Tong Fan et al. disclosed a transition of a mode transitioner and a cascaded slotted mode filter (Tong Fan, Liu Changjun, A high-power 8 mm microwave transmission system based on overmode waveguide, Journal of Terahertz Science and Electronic Information, 2014(3): 416-419). The mode transitioner transitions the standard waveguide to the size of the overmode waveguide, minimizing the coupling from the main mode to higher-order modes as much as possible. The mode filter cuts the current of higher-order modes by slotting on the waveguide wall, thereby suppressing the generated even-order TE. m0 Pattern and TE mn TM mn This structure is only suitable for overmode waveguides of a certain size. However, as the size of the overmode waveguide increases further, TE... 30When higher-order modes can propagate, this structure cannot effectively suppress odd-order modes. In summary, existing rectangular waveguides cannot effectively suppress higher-order modes for TE. 30 Suppression of higher-order modes can be achieved, but problems such as long size and insufficient suppression may exist. Therefore, it is of great significance to carry out high-order mode suppression transition between novel rectangular single-mode waveguides and rectangular overmode waveguides. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-order mode suppression transition structure between a rectangular single-mode waveguide and a rectangular overmode waveguide based on two equal-power excitation odd-symmetric electric fields. This structure achieves high suppression while also having the advantages of miniaturization, lightweighting, and low cost.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is: a high-order mode suppression transition between a rectangular single-mode waveguide and a rectangular overmode waveguide based on two equal-power excitation odd-symmetric electric fields, comprising a rectangular waveguide power divider, a rectangular connecting waveguide, and a rectangular overmode waveguide; the rectangular waveguide power divider is a one-to-two equal-power waveguide power divider; the rectangular connecting waveguide includes rectangular connecting waveguide I and rectangular connecting waveguide II, which connect the two outputs of the rectangular waveguide power divider to the rectangular overmode waveguide.

[0012] Furthermore, the input and output ports of the rectangular waveguide power divider have a width greater than half the operating wavelength and less than the operating wavelength, and only transmit TE signals. 10 The width of rectangular waveguide I and rectangular waveguide II is also greater than half the operating wavelength but less than the operating wavelength, and only transmits TE. 10 The rectangular overmode waveguide has a wider side than the operating wavelength, and the output signal is of equal amplitude and in phase. 10 and TE 20 Model, or even higher TE 30 and TE 40 Patterns; these patterns have the same polarization direction.

[0013] Furthermore, the centers of the output wide sides of the rectangular connecting waveguide I and the rectangular connecting waveguide II are located at 1 / 3 and 2 / 3 of the width of the rectangular overmode waveguide, respectively, and their outputs correspond to the TE in the rectangular overmode waveguide. 30 At the odd-symmetric location of the mode electric field, the TE in the rectangular overmode waveguide is realized. 30 Mode suppression; simultaneously, TE in the rectangular overmode waveguides corresponding to rectangular connected waveguide I and rectangular connected waveguide II. k0 The electric fields of the modes (k being an even number greater than or equal to 2) are also odd-symmetric, thus achieving TE in a rectangular overmode waveguide. k0 Suppression of the modulus (k is an even number greater than or equal to 2).

[0014] The principle of the technical solution of this invention is as follows: the waveguide power divider is a 1-to-2 power divider, and the input port and output port only transmit TE signals. 10 When a single-mode waveguide excites the input port of a waveguide power divider, the entire power divider outputs two TE channels. 10 The two signals are transmitted from the rectangular connecting waveguide to the rectangular overmode waveguide, with both signals having equal amplitude and phase. The distance between the two output ports of the rectangular connecting waveguide is controlled so that the centers of the output wide sides of rectangular connecting waveguide I and rectangular connecting waveguide II are located at 1 / 3 and 2 / 3 of the width of the rectangular overmode waveguide, respectively. The excitation points of rectangular connecting waveguide I and rectangular connecting waveguide II are located at the rectangular overmode waveguide TE. 30 At the odd-symmetric point of the mode electric field, whether it is rectangular connected waveguide I or rectangular connected waveguide II, due to their respective excitation fields and TE in the rectangular overmode waveguide... 30 The field of the mode has opposite symmetry properties, TE 30 The mode is not excited. Furthermore, although both rectangular connected waveguide I and rectangular connected waveguide II can independently excite the TE in their respective rectangular overmode waveguides. k0 The modes (k is an even number greater than or equal to 2) transmit equal power and have the same phase. The excitation positions are symmetrical about the center of the rectangular overmode waveguide, resulting in equal magnitudes and opposite directions of the excitation fields. This exhibits odd symmetry and cancels each other out. Overall, TE... k0 The modulus (k being an even number greater than or equal to 2) also cannot be excited. This invention achieves TE suppression by controlling the two equal-power excitation fields and the field of the mode to be suppressed to have odd symmetry properties. 30 Model and TE k0 Suppression of modes (where k is an even number greater than or equal to 2), where neither path can excite TE. 30 Model, and TE k0 The mode is through a two-way excited TE k0 Mode suppression is achieved by mutual cancellation of modes.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0016] 1. This invention starts from the fact that the excitation field and the suppression mode field have opposite symmetry properties, and achieves TE suppression by controlling the position and amplitude of the excitation field. 30 The suppression of the mode solves the problem that traditional transition modes cannot effectively suppress TE. 30 The problem lies in the mode. Meanwhile, this invention employs two equal-power excitation paths to suppress TE. 30 Simultaneously implement the mode for TE k0 Suppression of modes (where k is an even number greater than or equal to 2). Additionally, matching can be easily achieved by controlling the output port size of the power divider, the connection waveguide length, and the port size control.

[0017] 2. Compared with the prior art, this invention has the advantages of small size, low cost and light weight, in addition to good electrical performance. It is easy to implement and has extremely high application value.

[0018] 3. This invention completely solves the problem of insufficient transition suppression in existing technologies, and theoretically has extremely high suppression of higher-order modes, filling a technological gap in the industry both domestically and internationally.

[0019] 4. The core idea of ​​this invention is to control the excitation field and the suppression mode field to have opposite symmetric properties, thus broadening the approach to suppressing other odd-numbered modes. Furthermore, its related dimensions can be adjusted according to the frequency band, power capacity, and other requirements of actual applications, demonstrating broad application prospects. Attached Figure Description

[0020] Figure 1 It is a rectangular waveguide TE 10 TE 20 TE 30 TE 40 Cross-sectional view of the electric field.

[0021] Figure 2 This is a schematic diagram showing the overall structure of the present invention.

[0022] Figure 3 This is a schematic diagram showing the overall structure of Embodiment 1 of the present invention.

[0023] Figure 4 The curves show the main model characteristic parameters of the overall structure of Embodiment 1 of the present invention at 26.7-29 GHz.

[0024] Figure 5 The curves show the high-order model characteristics of the overall structure of Embodiment 1 of the present invention at 26.7-29 GHz.

[0025] In the figure, 1-waveguide power divider, 2-rectangular connecting waveguide, 3-rectangular overmode waveguide, 4-rectangular overmode matching waveguide, 5-rectangular overmode main waveguide, 11-bottom metal wall of waveguide power divider 1, 21-rectangular connecting waveguide I, 22-rectangular connecting waveguide II. Detailed Implementation

[0026] To make the objectives, technical problems solved, and technical solutions of this invention clearer, the invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Example 1:

[0028] Figure 3This is a schematic diagram showing the structure of a specific embodiment of the present invention, including a rectangular waveguide power divider 1, a rectangular connecting waveguide 2, a rectangular overmode waveguide 3, a rectangular overmode matching waveguide 4, and a rectangular overmode main waveguide 5. The waveguide power divider 1 is an HT structure, realizing TE... 10 While ensuring equal power and in-phase output of the mode, the matching of the input ports is also guaranteed. The rectangular connecting waveguide 2 includes rectangular connecting waveguide I 21 and rectangular connecting waveguide II 22. In order to make the output port positions of rectangular connecting waveguide I 21 and rectangular connecting waveguide II 22 controllable, both rectangular connecting waveguides are bent three times at 90 degrees. The input ports of the two connecting waveguides are respectively connected to the two output ports of the waveguide power divider 1. The two output ports are simultaneously used to feed the input port of the rectangular overmode waveguide 3, and the two connecting waveguides are completely symmetrical, ensuring equal power and in-phase excitation of the rectangular overmode waveguide 3. The input end of the rectangular overmode matching waveguide 4 is connected to the rectangular overmode waveguide 3, and the output end is connected to the rectangular overmode main waveguide 5. Its main function is to ensure that the entire transition has good reflection characteristics in the working frequency band.

[0029] Furthermore, the input port of the waveguide power divider 1 is a standard BJ260 waveguide port with dimensions of 8.636mm × 4.318mm, and the two output ports are waveguide ports with shortened wide sides, each with dimensions of 6mm × 4.318mm. At the symmetrical center of the waveguide power divider 1, there is a capacitively loaded metal conductor pillar with a radius of 0.26mm, and the center of the pillar is 3.68mm from the bottom metal wall 11 of the waveguide power divider. The rectangular connecting waveguide I 21 and rectangular connecting waveguide II 22 both have a cross-sectional dimension of 6mm × 4.318mm at non-bending points. The two rectangular connecting waveguides have symmetrical dimensions to ensure that the output excitation signal has the same phase. At the three 90-degree bends, a rounded chamfer structure with a radius of 6.64mm is used to achieve good reflection characteristics. The rectangular overmode main waveguide 5 has dimensions of 25mm × 4.9mm and can transmit TE signals in the 26.7-29GHz operating frequency band. 20 TE 30 TE 40 mold.

[0030] Furthermore, the spacing between the two rectangular connecting waveguides is 2.33 mm. At this point, the center of the output ports of the two connecting waveguides is exactly located at the widths of the rectangular overmode waveguide 3 (8.33 mm and 16.66 mm), meaning the TE value under this rectangular overmode waveguide dimension is [value missing]. 30 At the zero point of the mode electric field, and with the electric fields on both sides of the zero point being oddly symmetrical, it is possible to achieve TE 30 Mode suppression; simultaneously, TE in rectangular overmode waveguide 3 corresponding to rectangular connecting waveguide I 21 and rectangular connecting waveguide II 22 20 Model / TE 40 The electric fields of the modes are also odd-symmetric, realizing the TE in the rectangular overmode waveguide 3. 20 Model, TE40 Suppression of the model.

[0031] Furthermore, the rectangular overmode waveguide 3 and the rectangular overmode matching waveguide 4 both have a wide side of 25mm, the narrow side and longitudinal dimensions of the rectangular overmode waveguide 3 are 4.87mm and 8.97mm respectively, and the narrow side and longitudinal dimensions of the rectangular overmode matching waveguide 4 are 2.24mm and 3.91mm respectively.

[0032] Figure 4 The characteristic parameter curves of the 26.7GHz-29GHz main mode in this specific embodiment are given. Figure 5 Characteristic parameter curves for the 26.7GHz-29GHz high-order modes in this specific embodiment are presented. The entire longitudinal dimension is only 62.14mm. If a linear wedge gradient structure is used to achieve the same 40dB high-order mode suppression, a length of more than 400mm is required.

[0033] Example 2:

[0034] In this embodiment, the waveguide power divider 1 used to achieve equal power distribution in Embodiment 1 is replaced with an orthogonal or reverse equal power divider. The length difference between the rectangular connecting waveguide I 21 and the rectangular connecting waveguide II 22 compensates for the output phase difference of the waveguide power divider 1. Other structures are the same as in Embodiment 1, and the function of the present invention can still be achieved.

[0035] Example 3:

[0036] In this embodiment, the narrow waveguide sides of the output port and input port of the waveguide power divider 1 are different from those in Embodiment 1, or the narrow waveguide sides of the output port and input port of the rectangular connecting waveguide 2 are different, or the narrow waveguide sides of the input port of the rectangular connecting waveguide 2 and the output port of the waveguide power divider 1 are different. Other structures are the same as in Embodiment 1, and the function of the present invention can still be realized.

[0037] Those skilled in the art will recognize that the embodiments described herein are for the purpose of better understanding the principles and operation of the invention, and should be understood as not limiting the scope of protection of the invention to such specific statements and embodiments. Any feature disclosed in this specification, unless specifically stated otherwise, may be replaced by other equivalent or similarly purposed alternative features; all disclosed features, or steps in all methods or processes, except for mutually exclusive features and / or steps, may be combined in any manner. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the essence of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A high-order mode suppression transition structure between a rectangular single-mode waveguide and a rectangular overmode waveguide based on two equal-power excitation odd-symmetric electric fields, comprising a rectangular waveguide power divider (1), a rectangular connecting waveguide (2), and a rectangular overmode waveguide (3); wherein, The rectangular connecting waveguide (2) includes rectangular connecting waveguide I (21) and rectangular connecting waveguide II (22), which connect the two outputs of the rectangular waveguide power divider (1) to the rectangular overmode waveguide (3); characterized in that: the rectangular waveguide power divider (1) is a one-to-two equal power in-phase waveguide power divider; the center of the output wide side of the rectangular connecting waveguide I (21) and the rectangular connecting waveguide II (22) is located at 1 / 3 and 2 / 3 of the wide side of the rectangular overmode waveguide (3), respectively; the wide side of the input port and the output port of the rectangular waveguide power divider (1) is greater than half of the working wavelength and less than the working wavelength, and only transmits TE. 10 The rectangular connecting waveguide I (21) and the rectangular connecting waveguide II (22) have a width greater than half the operating wavelength and less than the operating wavelength, and only transmit TE. 10 The rectangular overmode waveguide (3) has a wider side than the operating wavelength and can transmit TE signals with equal amplitude and phase. 10 and TE 20 Modes, and even higher modes; TE in rectangular waveguide power dividers (1) and rectangular connecting waveguides (2) 10 Mode, and TE in rectangular overmode waveguide (3) 10 TE 20 The polarization directions of the modes are the same.

2. The high-order mode suppression transition structure between a rectangular single-mode waveguide and a rectangular overmode waveguide based on two equal-power excitation odd-symmetric electric fields as described in claim 1, characterized in that: The outputs of both rectangular connected waveguide I (21) and rectangular connected waveguide II (22) correspond to the TE in the rectangular overmode waveguide (3). 30 At the odd-symmetric location of the mode electric field, the TE in the rectangular overmode waveguide (3) is realized. 30 Mode suppression, while the output wide side centers of rectangular connecting waveguide I (21) and rectangular connecting waveguide II (22) are symmetrical along the wide side center of the rectangular overmode waveguide (3), and the corresponding TE in the rectangular overmode waveguide (3) k0 The electric fields of the modes are also odd-symmetric, realizing the TE in the rectangular overmode waveguide (3). k0 The suppression of the modulus, where k is an even number greater than or equal to 2.

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