A dual-polarized wideband angular selective surface structure for in-band interference rejection

Abstract

The application belongs to the technical field of electromagnetic wave regulation and anti-interference, and specifically provides a dual-polarized broadband angle selective surface structure for same-frequency anti-interference, to solve the key technical problems of insufficient angle selectivity, limited working bandwidth and poor polarization adaptability of the existing angle selective structure in engineering application. The application proposes a structure design of multilayer metal plus polystyrene foam based on Jerusalem cross slots, realizes TE and TM dual-polarized working modes through innovative unit design and interlayer coupling mechanism; the multilayer metal arrangement realizes excellent angle selectivity and more than 6% working bandwidth while keeping a low profile, can keep low-loss transmission of incident waves at small-angle incidence, and keep stable angle selectivity and interference suppression performance at large-angle incidence; and the application has the significant advantages of good angle selectivity, wide working bandwidth, strong polarization adaptability, high structural stability and the like.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic wave modulation and anti-interference technology, and specifically provides a dual-polarized broadband angle-selective surface structure for anti-interference at the same frequency. Background Technology

[0002] In modern wireless communication and satellite navigation, co-channel interference has become a key bottleneck restricting the improvement of system performance. Traditional anti-interference technologies based on the frequency domain or time domain are difficult to effectively solve the problem of co-channel and co-polarized interference, while angle selection technology based on the spatial domain provides a new technical path to solve this problem.

[0003] Currently, the main technical approaches to achieving angle selectivity still have significant limitations. First, while Brewster angle-based designs can achieve good angle selectivity, the structural profile height often exceeds ten operating wavelengths, severely restricting their application in compact devices. Second, while designs using odd-mode resonance or multi-mode resonance can reduce the profile height, they typically only support single-polarization operation, failing to meet the dual-polarization requirements of modern communication systems. Third, while 3D-based designs can expand the operating bandwidth, they often suffer from poor angle selectivity and excessively large transition bandwidth. Furthermore, although multi-layer FSS structures improve angle selectivity to some extent, existing designs generally suffer from narrow operating bandwidth and a sharp deterioration in interference suppression when TM-polarized waves are incident at large angles. These technical bottlenecks severely limit the application effectiveness of angle-selective structures in practical engineering. Summary of the Invention

[0004] The purpose of this invention is to provide a dual-polarization broadband angle-selective surface structure for co-frequency interference suppression, addressing key technical problems faced by existing angle-selective structures in engineering applications, such as insufficient angle selectivity, limited operating bandwidth, and poor polarization adaptability. This invention proposes a multi-layered metal and polystyrene foam structure based on a Jerusalem cross-shaped slit. Through innovative unit design and interlayer coupling mechanism, it achieves dual-polarization operating modes for both TE and TM wavelengths. The multi-layered metal arrangement maintains a low profile (less than two operating wavelengths) while achieving excellent angle selectivity and an operating bandwidth exceeding 6%. It maintains low-loss (<-1dB) transmission of incident waves at small incident angles (0°–15°) and stable angle selectivity and interference suppression performance at large incident angles (30°–75°). Compared to existing technologies, this invention offers significant advantages such as good angle selectivity, wide operating bandwidth, strong polarization adaptability, and high structural stability. Furthermore, the use of metal processing and foam layers results in low manufacturing costs and high reliability, providing a practical engineering solution for co-frequency interference suppression applications.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A dual-polarized broadband angle-selective surface structure for co-frequency interference suppression is composed of several angle-selective surface units arranged in an array. The angle-selective surface unit comprises a lower FSS structure, a first intermediate FSS structure, a second intermediate FSS structure, and an upper FSS structure, stacked sequentially from bottom to top, with polystyrene foam layers filling the spaces between adjacent FSS structures. The lower, first, second, and upper FSS structures all employ the same structure, being metal plates with Jerusalem cross-shaped slits etched along their centers. The lower and upper FSS structures have the same dimensions, as do the first and second intermediate FSS structures.

[0007] Furthermore, in the lower and upper FSS structures, the gap width of the Jerusalem cross gap is W1, the arm length of the central gap is L2, and the arm length of the end loading gap is L1; in the first and second intermediate FSS structures, the gap width of the Jerusalem cross gap is W2, the arm length of the central gap is L4, and the arm length of the end loading gap is L3; therefore, L2>L1, L4>L3, and W1>W2.

[0008] Furthermore, the polystyrene foam layers between the lower FSS structure and the first intermediate FSS structure, and between the upper FSS structure and the second intermediate FSS structure, have the same thickness.

[0009] Furthermore, the side length P of the angle-selected surface unit is 45mm.

[0010] Furthermore, in the lower FSS structure and the upper FSS structure, the gap width W1 of the Jerusalem cross gap is 5.3mm, the central gap arm length L2 is 36mm, and the end loading gap arm length L1 is 20mm.

[0011] Furthermore, in the first intermediate layer FSS structure and the second intermediate layer FSS structure, the gap width W2 of the Jerusalem cross gap is 2mm, the central gap arm length L4 is 35mm, and the end loading gap arm length is L3 is 21.5mm.

[0012] Furthermore, the thickness of the polystyrene foam layer between the lower FSS structure and the first intermediate FSS structure, and between the upper FSS structure and the second intermediate FSS structure, is H1, where H1 = 49 mm; the thickness of the polystyrene foam layer between the first intermediate FSS structure and the second intermediate FSS structure is H2 = 51.3 mm.

[0013] Furthermore, the lower FSS structure, the first intermediate FSS structure, the second intermediate FSS structure, and the upper FSS structure are all made of aluminum plates with a thickness h = 0.25 mm.

[0014] Based on the above technical solution, the beneficial effects of the present invention are as follows:

[0015] This invention provides a dual-polarized broadband angle-selective surface structure for co-frequency interference suppression. This structure employs an innovative multi-layered metal periodic array design, which, through precise control of electromagnetic wave transmission characteristics, effectively suppresses co-frequency interference signals in complex electromagnetic environments. Its core working principle can be explained in detail below:

[0016] When electromagnetic waves are incident at any angle θ, this structure can independently control both TE-polarized (electric field along the x-axis) and TM-polarized (magnetic field along the y-axis) electromagnetic waves. Under normal incidence, the structure exhibits excellent broadband transmission characteristics, with an operating bandwidth exceeding 6% of the center frequency. Under oblique incidence, through a unique electromagnetic resonance mechanism, it significantly reflects co-frequency interference signals in specific frequency bands, achieving a combined space-frequency domain filtering function. This structure employs a multi-layer Jerusalem cross-slot array design, achieving broadband operation characteristics within a profile smaller than two operating wavelengths through precisely optimized unit structure and interlayer spacing. Based on equivalent circuit model analysis, this structure can be equivalent to a frequency-dependent variable susceptance network, whose impedance characteristics exhibit adaptive adjustment with changing incident angles: a matched state under normal incidence, achieving efficient wave transmission; and a mismatch under oblique incidence, resulting in interference reflection. This intelligent impedance control mechanism is the core of the structure's co-frequency interference suppression.

[0017] Compared with existing technologies, the innovation of this invention is mainly reflected in the following aspects: First, by adopting a metallized design and abandoning the traditional dielectric substrate, it not only has higher power capacity but also significantly improves environmental stability, maintaining stable performance over a wide temperature range. Second, through an innovative multi-layer Jerusalem cross-shaped slot unit optimized structure, dual-polarization broadband operation is achieved while maintaining a low profile, with a working bandwidth covering 3.2-3.4GHz, fully meeting current communication anti-interference requirements. Third, the unique impedance gradient characteristics ensure stable interference suppression performance even at large incident angles (30° to 75°), with significantly improved angle selectivity compared to traditional structures. Furthermore, this structure is entirely passive, avoiding phase noise and additional interference introduced by active devices, with an insertion loss of less than 1dB and an out-of-band rejection ratio better than 20dB. In practical applications, this structure can be easily integrated into radomes or radar array surfaces, making it particularly suitable for applications with strict requirements for co-channel interference suppression, such as 5G communication, satellite navigation, and airborne radar. Test results show that in complex electromagnetic environments, this structure can improve the system's anti-interference capability by more than 15dB, providing an innovative solution to the co-channel interference problem faced by modern wireless systems. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the dual-polarized broadband angle-selective surface structure used for anti-interference at the same frequency in this invention.

[0019] Figure 2 This is a schematic diagram of the unit structure of the dual-polarized broadband angle-selective surface structure used for anti-interference at the same frequency in this invention.

[0020] Figure 3 This is a graph showing the transmission coefficient of the incident wave at different incident angles in TE mode according to the present invention.

[0021] Figure 4 This is a graph showing the transmission coefficient of the incident wave at different incident angles in TM mode according to the present invention.

[0022] Figure 5 The graph shows the angle selection performance of the present invention in TE polarization mode and TM polarization mode. Detailed Implementation

[0023] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] To facilitate a thorough understanding of the technical solutions of this invention by those skilled in the art, specific embodiments of this invention will now be described in detail with reference to the accompanying drawings. It should be particularly noted that the following embodiments are merely illustrative of the technical principles and implementation methods of this invention and do not constitute any limitation on the scope of protection of this invention. Based on the fundamental principles of this invention, any equivalent modifications or improvements made by those skilled in the art without creative effort should be included within the scope of protection of this invention. In the specific description, to avoid redundant descriptions of common knowledge affecting the understanding of the core technology of this invention, some conventional technical details will be appropriately omitted.

[0025] The accompanying drawings of this invention illustrate relevant structural diagrams. It should be noted that the drawings are not strictly to scale; some details have been appropriately enlarged for clarity, and some non-critical details may be simplified. The functional areas, structural layers, and their relative dimensions and positional relationships shown in the drawings are for illustrative purposes only, and reasonable deviations may exist in actual implementation due to process tolerances or technical limitations. Those skilled in the art can adaptively adjust the shape, size, and spatial layout of the illustrated structures according to specific application requirements; all such reasonable modifications should fall within the protection scope of this invention.

[0026] Specifically, this embodiment provides a dual-polarized broadband angle-selective surface structure for co-frequency anti-interference, the structure of which is as follows: Figure 1 As shown, it is composed of 100 angle-selective surface units arranged in a 10×10 array; the angle-selective surface unit is as follows: Figure 2 As shown, the structure includes a lower FSS structure, a first intermediate FSS structure, a second intermediate FSS structure, and an upper FSS structure stacked sequentially from bottom to top, with polystyrene foam layers filling the spaces between adjacent FSS structures. The lower FSS structure, the first intermediate FSS structure, the second intermediate FSS structure, and the upper FSS structure all adopt the same structure, specifically a metal plate with a Jerusalem cross etched along its center. The lower FSS structure and the upper FSS structure have the same dimensions, as do the first intermediate FSS structure and the second intermediate FSS structure, including the dimensions of the metal plate and the Jerusalem cross etched.

[0027] Furthermore, the side length of the surface unit is selected as P = 45mm, that is, the side length of the lower FSS structure, the first intermediate FSS structure, the second intermediate FSS structure and the upper FSS structure are all P.

[0028] Furthermore, the lower FSS structure, the first intermediate FSS structure, the second intermediate FSS structure, and the upper FSS structure all use aluminum plates with a thickness h = 0.25 mm.

[0029] Furthermore, in the lower and upper FSS structures, the gap width W1 of the Jerusalem cross gap is 5.3 mm, the central gap arm length L2 is 36 mm, and the end loading gap arm length L1 is 20 mm.

[0030] Furthermore, in the first intermediate layer FSS structure and the second intermediate layer FSS structure, the gap width W2 of the Jerusalem cross gap is 2mm, the central gap arm length L4 is 35mm, and the end loading gap arm length is L3 is 21.5mm.

[0031] Furthermore, the thickness of the polystyrene foam layer between the lower FSS structure and the first intermediate FSS structure is H1 = 49 mm, and the thickness of the polystyrene foam layer between the upper FSS structure and the second intermediate FSS structure is H1 = 49 mm, that is, the thickness of the polystyrene foam layer between the lower FSS structure and the first intermediate FSS structure, and between the upper FSS structure and the second intermediate FSS structure is the same; the thickness of the polystyrene foam layer between the first intermediate FSS structure and the second intermediate FSS structure is H2 = 51.3 mm.

[0032] The beneficial effects of the present invention will be explained in detail below with reference to simulation tests.

[0033] Using the commercial finite element electromagnetic simulation software ANSYS Electronics 2021R1, the transmission coefficient of the dual-polarized broadband angle-selective surface structure in the implementation case was simulated and calculated under different incident angles in TE polarization mode. The results are as follows: Figure 3 As shown.

[0034] Using the commercial finite element electromagnetic simulation software ANSYS Electronics 2021R1, the transmission coefficient of the dual-polarized broadband angle-selective surface structure in the implementation case was simulated and calculated under different incident angles in TM polarization mode. The results are as follows: Figure 4 As shown.

[0035] The angle selection performance of the dual-polarized broadband angle-selective surface structure in the implementation case was simulated using the commercial finite element electromagnetic simulation software ANSYS Electronics 2021R1 under TE and TM polarization modes. The results are as follows: Figure 5 As shown.

[0036] like Figure 3As shown in the figure, the horizontal axis represents frequency and the vertical axis represents transmission coefficient. As can be seen from the simulation results, the transmission characteristic curve of this structure is in the working center frequency band of 3.3GHz. When the incident angle θ of the TE-polarized electromagnetic wave is near 0°, the transmission coefficient varies from 0dB to -1dB, realizing the passband characteristics. When the incident angle θ of the TE-polarized electromagnetic wave is ≥30°, the transmission coefficient varies from -20dB to -100dB, realizing the bandstop characteristics. This shows that the present invention has good angle selectivity.

[0037] like Figure 4 As shown in the figure, the horizontal axis represents frequency and the vertical axis represents transmission coefficient. As can be seen from the simulation results, the transmission characteristic curve of this structure is in the working center frequency band of 3.3GHz. When the incident angle θ of the TM polarized electromagnetic wave is near 0°, the transmission coefficient varies from 0dB to -1dB, realizing the passband characteristics. When the incident angle θ of the TM polarized electromagnetic wave is ≥30°, the transmission coefficient varies from -20dB to -100dB, realizing the bandstop characteristics. This shows that the present invention has good angle selectivity.

[0038] like Figure 5 As shown in the figure, the horizontal axis represents the frequency and the vertical axis represents the transmission coefficient. The simulation results show that when the transmission coefficient characteristic curve of this structure is in the operating frequency band of 3.2GHz to 3.4GHz, the electromagnetic wave achieves a bandpass characteristic that changes from 0dB to -1dB in the incident angle range of -15° to +15°. At the same time, the bandstop characteristic changes between -20dB and -120dB in the incident angle ranges of -30° to -75° and +30° to +75°. It also has good angular selectivity in both vertical and horizontal polarization directions.

[0039] In summary, this invention provides a dual-polarization broadband angle-selective surface structure for co-frequency interference suppression. Based on a passive frequency-selective surface structure, it achieves good angle selectivity in both vertical and horizontal polarization directions. Adjusting the structural dimensions allows for different operating frequency bands, expanding its application range. Compared to other co-frequency interference suppression technologies, the system structure is simple, without introducing redundant active structures. It suppresses co-frequency interference without introducing additional interference sources. Furthermore, the dual-polarization angle-selective surface of this invention employs an all-metal design, offering good applicability, high reliability, and low cost.

[0040] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A dual-polarized broadband angle-selective surface structure for co-frequency interference suppression, comprising a plurality of angle-selective surface units arranged in an array; characterized in that, The angle-selective surface unit includes a lower FSS structure, a first intermediate FSS structure, a second intermediate FSS structure, and an upper FSS structure stacked sequentially from bottom to top, with polystyrene foam layers filling the spaces between adjacent FSS structures. The lower, first, second, and upper FSS structures all employ the same structure: a metal plate with a Jerusalem cross etched along its center, the Jerusalem cross etched coinciding with the centerline of the metal plate. The lower and upper FSS structures have the same dimensions, as do the first and second intermediate FSS structures. In the lower and upper FSS structures, the gap width of the Jerusalem cross gap is... W 1. The length of the center slit arm is L 2. The length of the end-loading slot arm is L 1; In the first intermediate layer FSS structure and the second intermediate layer FSS structure, the gap width of the Jerusalem cross gap is W 2. The length of the center slit arm is L 4. The length of the end-loading gap arm is L 3; then L 2 > L 1, L 4 > L 3, W 1 > W 2.

2. The dual-polarized broadband angle-selective surface structure for co-frequency anti-interference as described in claim 1, characterized in that, The polystyrene foam layers between the lower FSS structure and the first intermediate FSS structure, and between the upper FSS structure and the second intermediate FSS structure, have the same thickness.

3. The dual-polarized broadband angle-selective surface structure for co-frequency anti-interference as described in claim 1, characterized in that, The side length P of the angle-selected surface unit is 45 mm.

4. The dual-polarized broadband angle-selective surface structure for co-frequency anti-interference as described in claim 1, characterized in that, The gap width of the Jerusalem cross gap in the lower and upper FSS structures. W 1 = 5.3 mm, center slit arm length L 2 = 36 mm, end-loaded slot arm length L 1 = 20 mm.

5. The dual-polarized broadband angle-selective surface structure for co-frequency anti-interference according to claim 1, characterized in that, The gap width of the Jerusalem cross gap in the first intermediate FSS structure and the second intermediate FSS structure. W 2 = 2mm, center slit arm length L 4 = 35 mm, end loading slot arm length is L 3 = 21.5 mm.

6. The dual-polarized broadband angle-selective surface structure for co-frequency anti-interference according to claim 1, characterized in that, The thickness of the polystyrene foam layers between the lower FSS structure and the first intermediate FSS structure, and between the upper FSS structure and the second intermediate FSS structure, is [missing information]. H 1, H 1 = 49 mm; the thickness of the polystyrene foam layer between the first intermediate FSS structure and the second intermediate FSS structure. H 2 = 51.3 mm.

7. The dual-polarized broadband angle-selective surface structure for co-frequency anti-interference according to claim 1, characterized in that, The lower FSS structure, the first intermediate FSS structure, the second intermediate FSS structure, and the upper FSS structure are all made of aluminum plates, with a thickness of [missing information]. h = 0.25 mm.

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