A broadband, low-loss TE10-TE20 mode converter

Abstract

This invention discloses a broadband, low-loss TE10-TE20 mode converter, belonging to the field of millimeter-wave device technology. It includes a cuboid matching structure, a bed-of-nails structure, and an input E-plane rectangular waveguide, a tapered waveguide, and an output H-plane wide waveguide connected sequentially along a common bottom surface. The mode converter is divided into an upper cavity and a lower cavity along the upper bottom surface of the output H-plane wide waveguide. The input E-plane rectangular waveguide is divided into two halves, located in the upper and lower cavities respectively. The tapered waveguide includes a tapered height reduction waveguide and a tapered widening waveguide located in the upper and lower cavities respectively. The cuboid matching structure is located on the symmetry axis of the lower bottom surface of the tapered widening waveguide and is adjacent to the output H-plane wide waveguide. The bed-of-nails structure is located on both sides of the tapered widening waveguide and the output H-plane wide waveguide, outside the connection point between the input E-plane rectangular waveguide and the tapered widening waveguide. This invention effectively expands the operating bandwidth of the mode conversion, shortens the path length, and has the advantages of simple and compact structure, easy assembly, broadband operation, and low loss.

Description

Technical Field

[0001] This invention belongs to the field of millimeter-wave device technology, specifically relating to a broadband, low-loss TE10-TE20 mode converter. Background Technology

[0002] For various microwave / millimeter-wave waveguide systems, such as low-loss transmission systems, power combining systems, high-power electronic devices, microwave heating systems, and ultra-high-power radio frequency systems, it is often necessary to excite the desired waveguide modes or convert one waveguide mode to another. Among these, the TE10-TE20 mode converter is an important type of mode converter, often used as a higher-order mode combiner for circular waveguides and a spatial power combiner based on rectangular waveguides.

[0003] In the early stages of waveguide development, TE10-TE20 mode conversion was achieved using coupling holes and short-circuit pistons. Because these mode converters utilized the TE102 mode resonance of a single-mode waveguide, their bandwidth was very narrow. For tapered TE10-TE20 mode converters, the required circuit length was extremely long because a flat, slender structure was needed for efficient conversion from the TE10 mode to the TE20 mode. TE10-TE20 mode conversion using bent rectangular waveguides and chamfered corners, while compact, still had room for improvement in mode conversion efficiency and operating bandwidth. There were also mode converters with vertical input and output waveguides, which increased manufacturing and assembly difficulties because their waveguide directions were not aligned. Summary of the Invention

[0004] The purpose of this invention is to address the problems in the prior art by providing a broadband, low-loss TE10-TE20 mode converter that expands the operating bandwidth of mode conversion while effectively shortening the length of the mode conversion circuit. It has the advantages of simple and compact structure, easy assembly, broadband operation, and low loss.

[0005] The technical solution adopted in this invention is as follows:

[0006] A broadband, low-loss TE10-TE20 mode converter is characterized by comprising an input E-plane rectangular waveguide, a tapered waveguide, and an output H-plane wide waveguide that share a common bottom surface and are connected in sequence, and further comprising a cuboid matching structure and a bed of nails structure.

[0007] The TE10-TE20 mode converter has a planar symmetrical structure, which is divided into an upper cavity and a lower cavity along the upper bottom surface of the output H-plane wide waveguide.

[0008] The input E-plane rectangular waveguide is divided into two halves, located in the upper cavity and the lower cavity respectively;

[0009] The gradient waveguide includes a gradient height reduction waveguide located in the upper cavity and a gradient widening waveguide located in the lower cavity;

[0010] The cuboid matching structure is located on the symmetrical axis of the lower bottom surface of the gradient widening waveguide and is adjacent to the output H-plane wide waveguide.

[0011] The nail bed structure is located on both sides of the gradient-widened waveguide and the output H-plane wide waveguide, as well as on the outside of the connection between the input E-plane rectangular waveguide and the gradient-widened waveguide.

[0012] Furthermore, the input E-plane rectangular waveguide is a standard rectangular waveguide with a cross-sectional aspect ratio of 2:1; the output H-plane wide waveguide has a cross-sectional aspect ratio of 4:1.

[0013] Furthermore, the length of the gradient reduction waveguide is 1.5 to 1.7 times the wavelength, and the height ratio at both ends is 3:1; the length of the gradient widening waveguide is 1.2 to 1.8 times the wavelength, and the width ratio at both ends is 1:4.

[0014] Furthermore, the length of the cuboid matching structure is equal to the length of the tapered waveguide. Width is Double the wavelength, with a height equal to the height of the graded-widened waveguide.

[0015] Furthermore, the nail bed structure includes at least two rows of square nails, with the inner row of square nails aligned with the corresponding waveguide wall.

[0016] Furthermore, the nail bed structure is also disposed on both sides of the input E-plane rectangular waveguide, at a distance from the connection point with the gradually widened waveguide. At the wavelength position, there is at least one row of square nails.

[0017] Furthermore, the height and period of the square nail are both Double the wavelength.

[0018] The working principle of the broadband low-loss TE10-TE20 mode converter described in this invention is as follows:

[0019] When the dominant TE10 mode is transmitted in the E-plane rectangular waveguide, as it is transmitted to the graded waveguide, the transmission conditions of the TE10 mode are broken as the waveguide height gradually decreases, forcing the TE10 mode to convert to other modes. Simultaneously, the width of the graded widening waveguide increases, providing conditions for the TE10 mode to convert to the TE20 mode. When the width of the graded widening waveguide increases to meet the transmission conditions of the TE20 mode, the TE10 mode is completely converted to the TE20 mode. The addition of a rectangular matching structure helps to achieve efficient and wideband mode conversion. The simple and symmetrical structure of the graded waveguide results in high mode conversion purity.

[0020] Since the upper and lower surfaces of the output H-plane wide waveguide are split, when there are split gaps, the waveguide profile forms a high-resistivity surface due to the presence of the bed of nails structure. Electromagnetic waves in a specific frequency range cannot propagate in all directions, thereby reducing the transmission loss of the waveguide split gaps. Since gaps are allowed on the assembly surfaces of the upper and lower cavities, the requirements for processing accuracy and assembly error are reduced.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention proposes a broadband, low-loss TE10-TE20 mode converter. Mode conversion is achieved using a tapered waveguide composed of tapered decreasing and tapered widening waveguides. A cuboid matching structure is incorporated within the waveguide to effectively extend the operating bandwidth and shorten the path length. Furthermore, an array-arranged bed-of-pins structure effectively reduces assembly difficulty and electromagnetic leakage losses caused by waveguide partitioning, thereby simplifying the installation process and reducing transmission loss. This invention offers advantages such as simple and compact structure, ease of assembly, broadband operation, and low loss. Attached Figure Description

[0023] Figure 1 A three-dimensional structural diagram of the broadband low-loss TE10-TE20 mode converter provided in Embodiment 1 of the present invention;

[0024] Figure 2 This is a top view of the broadband low-loss TE10-TE20 mode converter provided in Embodiment 1 of the present invention.

[0025] Figure 3 This is a front view of the broadband low-loss TE10-TE20 mode converter provided in Embodiment 1 of the present invention;

[0026] Figure 4 Left view of the broadband low-loss TE10-TE20 mode converter provided in Embodiment 1 of the present invention;

[0027] Figure 5 The right view of the broadband low-loss TE10-TE20 mode converter provided in Embodiment 1 of the present invention;

[0028] Figure 6 The electric field distribution diagram of the broadband low-loss TE10-TE20 mode converter provided in Embodiment 1 of the present invention at a frequency of 220 GHz.

[0029] Figure 7 Comparison of S-parameter simulation results of the broadband low-loss TE10-TE20 mode converter provided in Embodiment 1 of the present invention, with and without a matched cube, applied to the WR-4.3 waveguide band;

[0030] The labels in the attached diagram are explained as follows:

[0031] 1: Upper cavity; 2: Lower cavity; 3: Input E-plane rectangular waveguide; 41: Gradual widening waveguide; 42: Gradual height reduction waveguide; 5: Output H-plane wide waveguide; 6: Cuboid matching structure; 7: Bed of nails structure. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] Example 1

[0034] This embodiment provides a broadband, low-loss TE10-TE20 mode converter operating in the 170–260 GHz frequency band, with the structure as follows: Figures 1-5 As shown, it includes an input E-plane rectangular waveguide 3, a gradient waveguide, and an output H-plane wide waveguide 5 connected in sequence with a common bottom surface, and also includes a cuboid matching structure 6 and a bed of nails structure 7.

[0035] The TE10-TE20 mode converter has a planar symmetrical structure and is divided into an upper cavity 1 and a lower cavity 2 along the upper bottom surface of the output H-plane wide waveguide 5.

[0036] The input E-plane rectangular waveguide 3 is divided into two halves, located in the upper cavity 1 and the lower cavity 2 respectively;

[0037] The gradient waveguide includes a gradient height reduction waveguide 42 located in the upper cavity 1 and a gradient widening waveguide 41 located in the lower cavity 2.

[0038] The cuboid matching structure 6 is located on the symmetrical axis of the lower bottom surface of the tapered widening waveguide 41 and is adjacent to the output H-plane wide waveguide 5.

[0039] The nail bed structure 7 is disposed on both sides of the tapered widening waveguide 41 and the output H-plane widening waveguide 5, and on the outer side of the connection between the input E-plane rectangular waveguide 3 and the tapered widening waveguide 41. Each side of the nail bed structure 7 has two rows of square nails, with the inner row of square nails aligned with the corresponding waveguide wall. The nail bed structure 7 is also disposed on both sides of the input E-plane rectangular waveguide 3, at a distance from the connection between it and the tapered widening waveguide 41. At the wavelength position, there is a row of square nails.

[0040] In this embodiment, the input E-plane rectangular waveguide 3 is a standard rectangular waveguide of model WR-4.3, with a cross-sectional length and width of 1.092mm × 0.546mm; the output H-plane wide waveguide 5 has a cross-sectional length and width of 2.184mm × 0.546mm; the tapered reduction waveguide 42 has a length of 1.876mm, and heights at both ends of 0.546mm and 0.184mm, respectively; the tapered widening waveguide 41 has a length of 1.75mm, and widths at both ends of 0.546mm and 2.184mm, respectively; the cuboid matching structure 6 has a length of 0.546mm, a width of 0.345mm, and a height of 0.156mm; the square nail has a height of 0.32mm, a side length of 0.2mm, and a period of 0.4mm for the nail bed structure 7.

[0041] Furthermore, to facilitate processing and manufacturing, the inner right angle of the gradient reduction waveguide 42 is rounded by 0.1mm.

[0042] This embodiment uses three-dimensional electromagnetic simulation software to precisely design the dimensions of the broadband low-loss TE10-TE20 mode converter. To facilitate verification of the low-loss transition performance of this embodiment, the proposed broadband low-loss TE10-TE20 mode converter is applied to the 170-260GHz frequency band corresponding to the WR-4.3 waveguide for simulation. To accurately simulate the situation where the upper cavity and lower cavity are not tightly connected in actual assembly, a gap of 0.01mm is reserved between the horizontal contact surfaces of the upper cavity 1 and the lower cavity 2.

[0043] Simulated electric field distribution as follows Figure 6 As shown, the TE10-TE20 mode converter can effectively achieve the mode conversion from TE10 mode to TE20 mode, and the electric field in the waveguide (input E-plane rectangular waveguide 3, gradually widened waveguide 41, output H-plane wide waveguide 5) is effectively confined within the inner row of square pins and the inside of the waveguide, and the air gap does not cause electromagnetic leakage.

[0044] S-parameter simulations were performed on the TE10-TE20 mode converter with and without the cuboid matching structure 6 proposed in this embodiment. The results are as follows: Figure 7 As shown, at operating frequencies of 174–254 GHz, the TE10-TE20 mode converter with cuboid matching structure 6 exhibits an input return loss exceeding 20 dB, an insertion loss below 0.05 dB, a mode conversion efficiency as high as 98.86%, and a relative bandwidth of 37.3%. This indicates that, on the same scale, the TE10-TE20 mode converter with cuboid matching structure 6 achieves optimized and improved performance in terms of return loss, insertion loss, and operating bandwidth, demonstrating the effectiveness of cuboid matching structure 6 in enhancing device performance.

[0045] In summary, the broadband low-loss TE10-TE20 mode converter proposed in this embodiment introduces a cuboid matching structure, which expands the operating bandwidth; the waveguide profile allows for gaps, reducing the requirements for processing and assembly precision, and has the advantages of simple and compact structure, easy assembly, broadband operation and low loss.

[0046] The above embodiments are only for illustrating the principles and advantages of the present invention, and are not intended to limit the present invention. They are only for helping to understand the principles of the present invention. The scope of protection of the present invention is not limited to the above configurations and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the disclosed technology without departing from the essence of the present invention, but they are still within the scope of protection of the present invention.

Claims

1. A broadband, low-loss TE10-TE20 mode converter, characterized in that, It includes an input E-plane rectangular waveguide, a graded waveguide, and an output H-plane wide waveguide that share a common bottom surface and are connected in sequence, as well as a cuboid matching structure and a bed of nails structure; The TE10-TE20 mode converter has a planar symmetrical structure, which is divided into an upper cavity and a lower cavity along the upper bottom surface of the output H-plane wide waveguide. The input E-plane rectangular waveguide is divided into two halves, located in the upper cavity and the lower cavity respectively; The gradient waveguide includes a gradient height reduction waveguide located in the upper cavity and a gradient widening waveguide located in the lower cavity; the gradient height reduction waveguide is connected to half of the input E-plane rectangular waveguide located in the upper cavity; the gradient widening waveguide is connected to the other half of the input E-plane rectangular waveguide located in the lower cavity, and is also connected to the output H-plane wide waveguide. The cuboid matching structure is located on the symmetrical axis of the lower bottom surface of the gradient widening waveguide and is adjacent to the output H-plane wide waveguide. The nail bed structure is located on both sides of the gradient-widened waveguide and the output H-plane wide waveguide, as well as on the outside of the connection between the input E-plane rectangular waveguide and the gradient-widened waveguide.

2. The broadband low-loss TE10-TE20 mode converter according to claim 1, characterized in that, The aspect ratio of the input E-plane rectangular waveguide is 2:1, and the aspect ratio of the output H-plane wide waveguide is 4:

1.

3. The broadband low-loss TE10-TE20 mode converter according to claim 1, characterized in that, The length of the gradient reduction waveguide is 1.5 to 1.7 times the wavelength, and the height ratio at both ends is 3:1; the length of the gradient widening waveguide is 1.2 to 1.8 times the wavelength, and the width ratio at both ends is 1:

4.

4. The broadband low-loss TE10-TE20 mode converter according to claim 1, characterized in that, The length of the cuboid matching structure is the length of the graded-widened waveguide. Width is Double the wavelength, with a height equal to the height of the graded-widened waveguide.

5. The broadband low-loss TE10-TE20 mode converter according to claim 1, characterized in that, The nail bed structure includes at least two rows of square nails, with the inner row of square nails aligned with the corresponding waveguide wall.

6. The broadband low-loss TE10-TE20 mode converter according to claim 5, characterized in that, The nail bed structure is also located on both sides of the input E-plane rectangular waveguide, at a distance from the connection point with the gradually widened waveguide. At the wavelength position, there is at least one row of square nails.

7. The broadband low-loss TE10-TE20 mode converter according to claim 6, characterized in that, The height and period of the square nail are both Double the wavelength.

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