A G-band waveguide bandpass filter based on SSPP

Abstract

The present invention discloses a G-band waveguide bandpass filter based on SSPP, belonging to the technical field of filters. It includes a standard rectangular waveguide and an SSPP cell array located at the center of the E-plane of the standard rectangular waveguide. The SSPP cell array includes N levels of transmission SSPP cells with the same structural size arranged at equal intervals along the signal transmission direction. The transmission SSPP cell is a rotationally symmetric structure, specifically a rectangular metal sheet structure with grooves opened on both long sides. The length of the rectangular metal sheet structure is the same as the short side dimension of the standard rectangular waveguide, and the depth of the two grooves is greater than half of the width of the rectangular metal sheet structure. The designed transmission SSPP cell of the present invention has a natural bandpass characteristic, and it can achieve G-band bandpass filtering based on SSPP without combining with other structures having high-pass filtering characteristics, having the advantages of high design flexibility, low processing cost, small device size, and easy parameter adjustment.

Description

Technical Field

[0001] The present invention belongs to the technical field of filters, and particularly relates to a G-band waveguide bandpass filter based on SSPP. Background Art

[0002] Terahertz waves are exactly between the microscopic quantum theory and the macroscopic classical theory. Due to their special position, terahertz waves can exhibit many unique characteristics different from other types of electromagnetic radiation, which determines that terahertz waves have broad and good application prospects in many fields. Existing experiments and theoretical analyses show that there are four atmospheric transmission windows at 35 GHz, 94 GHz, 140 GHz, and 220 GHz in the millimeter-wave and near-terahertz frequency bands. At the current technical level, due to the unacceptable losses of traditional microstrip lines and substrate integrated waveguides in the near-terahertz frequency band, waveguide structures have advantages such as high power capacity and low loss compared with them, and their sizes are smaller in the terahertz frequency band. Therefore, waveguides are widely used as transmission lines in terahertz systems. Thus, the research on a series of microwave devices based on waveguides in the terahertz frequency band is booming.

[0003] As a frequency selection device, a filter suppresses useless signals while retaining useful signals as much as possible, and is widely used in fields such as satellite communication, mobile communication, radar systems, navigation systems, electronic countermeasures, and wireless telemetry, and plays a very important role in modern communication systems. Since the performance of the filter directly affects the performance of the entire communication system, with the increasingly complex electromagnetic environment and the increasingly serious frequency congestion, the performance requirements for filters are also getting higher and higher.

[0004] Surface Plasmon (SP) refers to the plasma oscillation between a metal and a dielectric. It can be excited by electrons or photons. Since it is itself the movement of charges, SP will create electromagnetic fields both inside and outside the metal.

[0005] Surface Plasmon Polaritons (SPP) refers to a hybrid excited state formed by the interaction of free electrons and photons on the metal surface at infrared or visible light frequencies, that is, SP excited by both electrons and photons, and the two are coupled to each other. As Figure 1 shown, SPP includes two kinds of movements. One is the charge movement on the metal surface, and the other is the electromagnetic wave in air or dielectric. Since the electromagnetic wave is confined between the metal and the dielectric, its energy can be well confined at the interface and belongs to a kind of surface wave. Figure 2 is a typical SPP dispersion curve graph. It can be seen that as the angular frequency ω increases, the wave vector k xThe value increases sharply, causing its wavelength to approach 0 and the group velocity to approach 0, that is, the plasma vibrates on the surface without moving (the group velocity is 0), indicating that SPP has a natural low-pass characteristic.

[0006] As a special electromagnetic wave in the optical frequency region, when the frequency drops to the far-infrared, terahertz, or microwave frequency bands, metals will be similar to perfect electrical conductors rather than plasmas with negative permittivity, making it impossible to excite SPP. Spoof Surface Plasmon Polaritons (SSPP) are achieved by etching patterns on the metal surface, such as hole or groove arrays, to form a periodic unit cell structure to realize the transmission of SPP-like waves in the terahertz or microwave frequency bands, as Figure 3 shown. And the characteristics of the SPP wave are determined by its periodic unit cell structure.

[0007] There have been many papers that implement low-pass filters by integrating SSPP on microstrip lines (Xu H, Zhao W-S, Wang D-W, et. Compact Folded SSPP Transmission Line and Its Applications in Low-Pass Filters[J]. IEEE Photonics Technology Letters, 2022, 34(11):591-594), substrate integrated waveguides (SIW) (Ji L, Li X-C, Mao J-F. Half-Mode Substrate Integrated Waveguide Dispersion Tailoring Using 2.5-D Spoof Surface Plasmon Polaritons Structure[J]. IEEE Transactions on Microwave Theory and Techniques, 2020, 68(7):2539-2550), or coplanar waveguides (CPW) (Ma H F, Shen X, Cheng Q, et. Broadband and high-efficiency conversion from guided waves to spoof surface plasmon polaritons[J]. Laser&Photonics Reviews, 2014, 8(1):146-151). There are also papers (Y. Liu, K.-D. Xu, J. Li, Y.-J. Guo, A. Zhang and Q. Chen, "Millimeter-Wave E-Plane Waveguide Bandpass Filters Based on Spoof Surface Plasmon Polaritons," in IEEE Transactions on Microwave Theory and Techniques, vol. 70, no. 10, pp. 4399-4409, Oct. 2022, doi:10.1109 / TMTT.2022.3197593) that propose implementing waveguide filters by etching an SSPP cell array on a 5880 substrate and then placing it on the E-plane of the waveguide. The structure is as shown in Figure 4As shown. Since substrates such as 5880 operate in the high-frequency band, especially above 110 GHz, their dielectric losses become unacceptable. Therefore, the above-mentioned achievements all work in the lower frequency band and all adopt the basic mode of SSPP, and other high-pass structures need to be combined to realize the band-pass filter.

[0008] At present, almost all waveguide band-pass filters in the G band (110 GHz - 300 GHz) are traditional coupled-resonator filters, which mainly consist of an input end, a coupling cavity, a resonant cavity, and an output end. The structure is as Figure 5 shown. It can be seen that the coupled-resonator filter needs to be composed of more resonant cavities, which will cause problems such as high processing cost and large device volume of the filter. Summary of the Invention

[0009] Aiming at the technical problems existing in the existing G-band waveguide band-pass filter, the present invention provides a G-band waveguide band-pass filter based on SSPP, which does not need to be combined with other high-pass structures, has natural band-pass characteristics, and can flexibly adjust the parameter characteristics of the band-pass filter only by changing the structural dimensions.

[0010] The technical solution adopted by the present invention is as follows:

[0011] A G-band waveguide band-pass filter based on SSPP includes a standard rectangular waveguide and an SSPP cell array located at the center of the E-plane of the standard rectangular waveguide; the SSPP cell array is a rotationally symmetric structure, including N transmission SSPP cells with the same structural dimensions arranged in equal periods along the signal transmission direction; N is a positive integer greater than or equal to 2.

[0012] Among them, the transmission SSPP cell is a rotationally symmetric structure, specifically a rectangular metal sheet structure with grooves opened on both long sides; the long side direction of the rectangular metal sheet structure is the short side direction of the standard rectangular waveguide, and the length is the same as the short side dimension of the standard rectangular waveguide; the depth directions of the two grooves are the wide side direction of the rectangular metal sheet structure, and the depth is greater than half of the width of the rectangular metal sheet structure.

[0013] Furthermore, by changing the groove depth in the transmission SSPP cell, the working frequency band of the G-band waveguide band-pass filter is adjusted. Specifically, as the groove depth in the transmission SSPP cell increases, the working frequency band of the G-band waveguide band-pass filter moves to the lower frequency.

[0014] Furthermore, by changing the distance between the two grooves in the transmission SSPP cell, the passband bandwidth of the G-band waveguide band-pass filter is adjusted. Specifically, as the groove distance in the transmission SSPP cell decreases, the passband bandwidth of the G-band waveguide band-pass filter gradually increases.

[0015] Further, the thickness of the rectangular metal sheet-like structure does not exceed 75 μm.

[0016] Further, the SSPP cell array further includes M-level first-end transition SSPP cells arranged at equal periods on one side of the N-level transmission SSPP cells, and M-level last-end transition SSPP cells arranged at equal periods on the other side of the N-level transmission SSPP cells; M is a positive integer; the periods of the M-level first-end transition SSPP cells, the M-level last-end transition SSPP cells, and the N-level transmission SSPP cells are the same;

[0017] Among them, both the first-end transition SSPP cells and the last-end transition SSPP cells are rotationally symmetric structures, specifically rectangular metal sheet-like structures with grooves opened on both long sides. Their structural dimensions are basically the same as those of the transmission SSPP cells, and the only difference from the transmission SSPP cells lies in the different distances between the two grooves. Specifically, the distance between the two grooves in the transmission SSPP cells is denoted as 2G g , starting from the first level, the distance between the two grooves in the M-level first-end transition SSPP cells gradually increases and transitions to 2G g , starting from the last level, the distance between the two grooves in the M-level last-end transition SSPP cells gradually increases and transitions to 2G g .

[0018] Further, the distances between the two grooves in both the first-end transition SSPP cells and the last-end transition SSPP cells are less than 2G g .

[0019] Further, there is no connection between adjacent first-end transition SSPP cells, transmission SSPP cells, and last-end transition SSPP cells.

[0020] Further, the structure of the groove is rectangular or L-shaped.

[0021] Further, when the structure of the groove is rectangular, the long sides of the two rectangular grooves are adjacent and parallel, and the length is greater than half of the width of the rectangular metal sheet-like structure.

[0022] Further, when the structure of the groove is rectangular, except for the distance between the two grooves, the other structural dimensions of the first-end transition SSPP cells, the transmission SSPP cells, and the last-end transition SSPP cells are the same.

[0023] Further, when the structure of the groove is L-shaped, the lower bottom sides of the two L-shaped grooves are adjacent and parallel, and the length of the lower bottom side is greater than half of the width of the rectangular metal sheet-like structure. The distance between the lower bottom sides of the two L-shaped grooves in the transmission SSPP cells is denoted as 2G g .

[0024] Furthermore, when the structure of the groove is L-shaped, chamfers are also made at both ends of the lower bottom edges of the two L-shaped grooves, which facilitates processing, enhances mechanical properties, and improves the performance of the filter.

[0025] The beneficial effects of the present invention are as follows:

[0026] The present invention proposes a G-band waveguide bandpass filter based on SSPP, which is designed by using a transmission SSPP cell structure with central connection and two-side grounding (referring to the connection of a rectangular metal sheet structure to a standard rectangular waveguide, and the length of the rectangular metal sheet structure is the same as the short-side dimension of the standard rectangular waveguide). It can be seen from the dispersion curve that it has a natural bandpass characteristic, and it can achieve G-band bandpass filtering based on SSPP without being combined with other structures with high-pass filtering characteristics. Moreover, by only changing the size of the groove in the transmission SSPP cell, the working frequency band and the passband bandwidth of the bandpass filter can be adjusted, and the design flexibility is higher. Compared with the traditional coupled-resonator filter, the present invention has the advantages of low processing cost, small device size, and easy parameter adjustment. Description of the Drawings

[0027] Figure 1 is the complete structure diagram of the waveguide bandpass filter based on SSPP proposed in Embodiment 1 of the present invention;

[0028] Figure 2 is the three-dimensional structure diagram of the central cross-sectional plane of the E-plane of the WR-4 waveguide in the waveguide bandpass filter based on SSPP proposed in Embodiment 1 of the present invention;

[0029] Figure 3 is the top view of the central cross-sectional plane of the E-plane of the WR-4 waveguide in the waveguide bandpass filter based on SSPP proposed in Embodiment 1 of the present invention;

[0030] Figure 4 is the size marking diagram of the transmission SSPP cell in Embodiment 1 of the present invention;

[0031] Figure 5 is the size numerical marking diagram of the transmission SSPP cell in Embodiment 1 of the present invention;

[0032] Figure 6 is the processing and assembly diagram of the waveguide bandpass filter based on SSPP proposed in Embodiment 1 of the present invention;

[0033] Figure 7 is the dispersion curve diagram of the waveguide bandpass filter based on SSPP proposed in Embodiment 1 of the present invention;

[0034] Figure 8 is the frequency response curve diagram of the waveguide bandpass filter based on SSPP proposed in Embodiment 1 of the present invention;

[0035] Figure 9 It is the electric field distribution diagram of the waveguide bandpass filter based on SSPP proposed in Embodiment 1 of the present invention at 220 GHz;

[0036] Figure 10 It is the three-dimensional structure diagram of the central sectional plane of the E-plane of the WR-6 waveguide in the waveguide bandpass filter based on SSPP proposed in Embodiment 2 of the present invention;

[0037] Figure 11 It is the top view of the central sectional plane of the E-plane of the WR-6 waveguide in the waveguide bandpass filter based on SSPP proposed in Embodiment 2 of the present invention;

[0038] Figure 12 It is the size numerical annotation diagram of the transmission SSPP cell in Embodiment 2 of the present invention;

[0039] Figure 13 It is the size numerical annotation diagram of the first-stage head-end transition SSPP cell and the second-stage tail-end transition SSPP cell in Embodiment 2 of the present invention;

[0040] Figure 14 It is the size numerical annotation diagram of the second-stage head-end transition SSPP cell and the first-stage tail-end transition SSPP cell in Embodiment 2 of the present invention;

[0041] Figure 15 It is the frequency response curve diagram of the waveguide bandpass filter based on SSPP proposed in Embodiment 2 of the present invention;

[0042] Figure 16 It is the electric field distribution diagram of the waveguide bandpass filter based on SSPP proposed in Embodiment 2 of the present invention at 140 GHz;

[0043] Figure 17 It is the waveguide bandpass filter based on SSPP proposed in Embodiment 3 of the present invention with the groove pitch 2G of the transmission SSPP cell g changing frequency response curve;

[0044] Figure 18 It is the waveguide bandpass filter based on SSPP proposed in Embodiment 3 of the present invention with the groove depth L of the transmission SSPP cell g changing frequency response curve;

[0045] The descriptions of the marks in the drawings are as follows:

[0046] 1: WR-4 waveguide; 2: First-stage head-end transition SSPP cell; 3: Second-stage head-end transition SSPP cell; 4: Transmission SSPP cell; 5: First-stage tail-end transition SSPP cell; 6: Second-stage tail-end transition SSPP cell; 7: Rectangular groove; 8: WR-6 waveguide; 9: L-shaped groove. Detailed implementation manners

[0047] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present 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 only used to explain the present invention and are not used to limit the present invention.

[0048] Embodiment 1

[0049] This embodiment provides a waveguide bandpass filter based on SSPP with a working frequency range of 210 GHz to 235 GHz. Its complete structure is as Figure 1 shown, including a WR-4 waveguide 1 and an SSPP cell array located at the E-plane center of the WR-4 waveguide 1. The size of the WR-4 waveguide 1 is 1092 μm × 546 μm.

[0050] The three-dimensional view of the E-plane central section plane of the WR-4 waveguide 1 of the waveguide bandpass filter is as Figure 2 shown, and the top view is as Figure 3 shown. It can be seen that the SSPP cell array is a rotationally symmetric structure, including two-stage first-end transition SSPP cells (i.e., the first-stage first-end transition SSPP cell 2 and the second-stage first-end transition SSPP cell 3) arranged in equal periods in sequence along the signal transmission direction, three-stage transmission SSPP cells 4 with the same structure size, and two-stage last-end transition SSPP cells (i.e., the first-stage last-end transition SSPP cell 5 and the second-stage last-end transition SSPP cell 6). The period D of the SSPP cell array u is 500 μm.

[0051] The first-end transition SSPP cells, the transmission SSPP cells 4, and the last-end transition SSPP cells are all rotationally symmetric structures, specifically rectangular metal sheet-like structures with rectangular grooves 7 opened on both long sides, as Figure 4 and Figure 5 shown. Except for the spacing between the two rectangular grooves 7, the other structural dimensions of the first-end transition SSPP cells, the transmission SSPP cells 4, and the last-end transition SSPP cells are the same.

[0052] Specifically, the long side direction of the rectangular metal sheet-like structure is the short side direction of the WR-4 waveguide 1, and the length L is the same as the short side dimension of the WR-4 waveguide 1, specifically 546 μm; the width D of the rectangular metal sheet-like structure is 300 μm, and the thickness is 50 μm; the depth direction of the two rectangular grooves 7 is the wide side direction of the rectangular metal sheet-like structure, and the depth L g is 250 μm, the width direction is the long side direction of the rectangular metal sheet-like structure, and the width D g is 40 μm.

[0053] The spacing between the two rectangular grooves 7 in the three - level transmission SSPP cell 4 (abbreviated as groove spacing) is the same, denoted as 2G g , specifically 2×65μm; in the two - level head - end transition SSPP cell and the two - level tail - end transition SSPP cell, the groove spacing of the first - level head - end transition SSPP cell 2 and the second - level tail - end transition SSPP cell 6 is 2×30μm, and the groove spacing of the second - level head - end transition SSPP cell 3 and the first - level tail - end transition SSPP cell 5 is 2×47μm. Thus, the groove spacing of the SSPP cells in the SSPP cell array shows a trend of first increasing and then decreasing.

[0054] As Figure 6 shown, the manufacturing process of the waveguide band - pass filter based on SSPP includes: first, use a milling cutter to mechanically process to obtain the WR - 4 waveguide 1, and use a high - speed milling cutter to perform an E - plane central dissection on the WR - 4 waveguide 1; then, use a 50 - μm - thick copper foil as the substrate, and use laser etching to etch the specific pattern of the SSPP cell array on the copper foil; finally, place the etched copper foil at the E - plane center of the WR - 4 waveguide 1 to obtain the assembled waveguide band - pass filter.

[0055] The dispersion curve of the waveguide band - pass filter based on SSPP proposed in this embodiment is as Figure 7 shown, and the frequency - response curve is as Figure 8 shown. It can be seen that the 3dB bandwidth of the obtained waveguide band - pass filter is 210GHz - 235GHz, the insertion loss is about - 1dB, and S 11 is below - 18dB within the passband.

[0056] Figure 9 This is the electric - field distribution diagram of the waveguide band - pass filter based on SSPP proposed in this embodiment at 220GHz. It can be seen that the obtained waveguide band - pass filter propagates the classical SPP surface wave at 220GHz.

[0057] Embodiment 2

[0058] This embodiment provides a waveguide band - pass filter based on SSPP with a working frequency range of 132GHz - 150GHz, including a WR - 6 waveguide 8 and an SSPP cell array located at the E - plane center of the WR - 6 waveguide 8. The size of the WR - 6 waveguide 8 is 1651μm×825μm.

[0059] The three - dimensional view of the E - plane central dissection plane of the WR - 6 waveguide 8 of the waveguide band - pass filter is as Figure 10 shown, and the top view is as Figure 11As shown, it can be seen that the SSPP cell array is a rotationally symmetric structure, including two levels of first - stage transition SSPP cells (i.e., the first - stage first - transition SSPP cell 2 and the second - stage first - transition SSPP cell 3) arranged at equal intervals in sequence along the signal transmission direction, three levels of transmission SSPP cells 4 with the same structure size, and two levels of end - transition SSPP cells (i.e., the first - stage end - transition SSPP cell 5 and the second - stage end - transition SSPP cell 6). The period D of the SSPP cell array u is 750 μm.

[0060] The first - transition SSPP cells, the transmission SSPP cells 4, and the end - transition SSPP cells are all rotationally symmetric structures, specifically rectangular metal sheet - like structures with L - shaped grooves 9 opened on both long sides; among them, the long - side direction of the rectangular metal sheet - like structure is the short - side direction of the WR - 6 waveguide 8, and the length L is the same as the short - side dimension of the WR - 6 waveguide 8, specifically 825 μm; the width D of the rectangular metal sheet - like structure is 450 μm, and the thickness is 50 μm; the lower bottom sides of the two L - shaped grooves 9 are adjacent and are arranged parallel to the wide side of the rectangular metal sheet - like structure, and the upper side is parallel to the long side of the rectangular metal sheet - like structure; chamfering is performed at both ends of the lower bottom side for easy processing.

[0061] The three - level transmission SSPP cells 4 have the same structure size. As Figure 12 shown, the length L of the lower bottom side of the L - shaped groove 9 g1 is 280 μm, the width D of the lower bottom side g1 is 60 μm, the length L of the upper side g2 is 260 μm, the width D of the upper side g2 is 60 μm; the distance 2G between the lower bottom sides of the two L - shaped grooves 9 g is 2×80 μm; the outer - end chamfering structure and the inner - end chamfering structure of the lower bottom side are both isosceles right - angled triangles, and the right - angled side length C1 of the outer - end chamfering is 50 μm, and the right - angled side length C2 of the inner - end chamfering is 50 μm.

[0062] Among the two levels of first - transition SSPP cells and the two levels of end - transition SSPP cells, the first - stage first - transition SSPP cell 2 and the second - stage end - transition SSPP cell 6 have the same structure size, and the second - stage first - transition SSPP cell 3 and the first - stage end - transition SSPP cell 5 have the same structure size.

[0063] In the first - stage first - transition SSPP cell 2 and the second - stage end - transition SSPP cell 6, as Figure 13 shown, the length L of the lower bottom side of the L - shaped groove 9 g1 is 315 μm, the width D of the lower bottom side g1 is 60 μm, the length L of the upper side g2 is 300 μm, the width D of the upper sideg2 is 60 μm; the distance 2G between the lower bottom edges of two L-shaped grooves 9 g is 2×60 μm; the chamfer structures at the outer end and the inner end of the lower bottom edge are both isosceles right triangles, the length C1 of the right-angled side of the outer-end chamfer is 155 μm, and the length C2 of the right-angled side of the inner-end chamfer is 50 μm.

[0064] In the second-stage first-end transition SSPP cell 3 and the first-stage last-end transition SSPP cell 5, as Figure 14 shown, the length L of the lower bottom edge of the L-shaped groove 9 g1 is 290 μm, the width D of the lower bottom edge g1 is 60 μm, the length L of the upper side edge g2 is 270 μm, the width D of the upper side edge g2 is 60 μm; the distance 2G between the lower bottom edges of two L-shaped grooves 9 g is 2×70 μm; the chamfer structures at the outer end and the inner end of the lower bottom edge are both isosceles right triangles, the length C1 of the right-angled side of the outer-end chamfer is 100 μm, and the length C2 of the right-angled side of the inner-end chamfer is 50 μm.

[0065] Furthermore, in the SSPP cell array, the distance between the lower bottom edges of the L-shaped grooves 9 of the SSPP cells shows a trend of increasing first and then decreasing, and the length of the lower bottom edge and the length of the upper side edge of the L-shaped grooves 9 also show a trend of increasing first and then decreasing.

[0066] The frequency response curve of the waveguide bandpass filter based on SSPP proposed in this embodiment is as Figure 15 shown. It can be seen that the 3dB bandwidth of the obtained waveguide bandpass filter is 132 GHz to 150 GHz, the insertion loss is about -1 dB, and S 11 in the passband is below -20 dB.

[0067] Figure 16 This is the electric field distribution diagram of the waveguide bandpass filter based on SSPP proposed in this embodiment at 140 GHz. It can be seen that the obtained waveguide bandpass filter propagates the classical SPP surface wave at 140 GHz.

[0068] Embodiment 3

[0069] This embodiment provides a waveguide bandpass filter based on SSPP. Compared with Embodiment 1, the difference is only that: it does not include two-stage first-end transition SSPP cells and two-stage last-end transition SSPP cells, that is, the SSPP cell array only includes three-stage transmission SSPP cells 4 with the same structural dimensions; other structures are the same.

[0070] Figure 17 This is for the waveguide bandpass filter based on SSPP obtained in this embodiment with the groove spacing 2G of the transmission SSPP cell 4g The varying frequency response curve shows that on the basis of the groove pitch 2G g being 140 μm and decreasing by 20 μm, the passband bandwidth of the waveguide bandpass filter can be increased by approximately 9 GHz.

[0071] Figure 18 For the waveguide bandpass filter based on SSPP obtained in this embodiment, with the groove depth L of the transmission SSPP cell 4 g varying, the frequency response curve shows that increasing the groove depth L g will cause the entire frequency band of the waveguide bandpass filter to continuously shift towards the low frequency.

[0072] The above embodiments only illustrate the principles and advantages of the present invention, rather than being used to limit the present invention. They are only for helping to understand the principles of the present invention. The protection scope of the present invention is not limited to the above configurations and embodiments. Those skilled in the art can make various other specific deformations and combinations without departing from the essence of the present invention, but still within the protection scope of the present invention.

Claims

1. A G-band waveguide bandpass filter based on SSPP, characterized in that, It includes a standard rectangular waveguide and an SSPP cell array located at the center of the E-plane of the standard rectangular waveguide; the SSPP cell array is a rotationally symmetric structure, including N levels of transmission SSPP cells with the same structure size arranged at equal intervals along the signal transmission direction; N is a positive integer greater than or equal to 2. Among them, the transmission SSPP cell is a rectangular metal sheet structure with grooves opened on both long sides; the long side direction of the rectangular metal sheet structure is the short side direction of the standard rectangular waveguide, and the length is the same as the short side size of the standard rectangular waveguide; the depth direction of the two grooves is the wide side direction of the rectangular metal sheet structure, and the depth is greater than half of the width of the rectangular metal sheet structure. The SSPP cell array also includes M levels of first-end transition SSPP cells arranged at equal intervals on one side of the N-level transmission SSPP cells, and M levels of end-end transition SSPP cells arranged at equal intervals on the other side of the N-level transmission SSPP cells; M is a positive integer. Among them, both the head-end transition SSPP cell and the tail-end transition SSPP cell are rotationally symmetric structures, specifically rectangular metal sheet structures with grooves on both long sides. The difference from the transmission SSPP cell lies in the different distances between the two grooves. Specifically, the distance between the two grooves in the transmission SSPP cell is denoted as 2G g , starting from the first stage, the distance between the two grooves in the M-stage head-end transition SSPP cell gradually increases and transitions to 2G g , starting from the last stage, the distance between the two grooves in the M-stage tail-end transition SSPP cell gradually increases and transitions to 2G g .

2. The G-band waveguide bandpass filter based on SSPP according to claim 1, wherein By changing the groove depth in the transmission SSPP cell, the working frequency band of the G-band waveguide bandpass filter is adjusted.

3. The G-band waveguide bandpass filter based on SSPP according to claim 1, wherein By changing the distance between the two grooves in the transmission SSPP cell, the passband bandwidth of the G-band waveguide bandpass filter is adjusted.

4. The G-band waveguide bandpass filter based on SSPP according to claim 1, characterized in that, The thickness of the rectangular metal sheet structure does not exceed 75 μm.

5. The G-band waveguide bandpass filter based on SSPP according to claim 1, characterized in that, The adjacent first-end transition SSPP cells, transmission SSPP cells, and end-end transition SSPP cells are not connected to each other.

6. The G-band waveguide bandpass filter based on SSPP according to claim 1, wherein The structure of the groove is rectangular or L-shaped.

7. The G-band waveguide bandpass filter based on SSPP according to claim 6, characterized in that, When the structure of the groove is rectangular, the long sides of the two rectangular grooves are adjacent and parallel, and the length is greater than half of the width of the rectangular metal sheet structure.

8. The G-band waveguide bandpass filter based on SSPP according to claim 6, wherein When the structure of the groove is L-shaped, the lower bottom edges of the two L-shaped grooves are adjacent and parallel, the length of the lower bottom edge is greater than half of the width of the rectangular metal sheet structure, and the distance between the lower bottom edges of the two L-shaped grooves in the SSPP transmission cell is denoted as 2G g .

9. The G-band waveguide bandpass filter based on SSPP according to claim 8, wherein, Chamfer the two ends of the lower bottom edge of the two L-shaped grooves.

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