A dual-polarization angle-selective surface structure for reducing radar sidelobes

Abstract

This invention discloses a dual-polarization angle-selective surface structure for reducing radar sidelobes, comprising an upper structure and a lower structure, with an air gap between them. Both the upper and lower structures include a plurality of frequency-selective surface units arranged in an array. Each frequency-selective surface unit includes a dielectric substrate. A first metal resonant unit structure is disposed on the upper surface of the dielectric substrate, and a second metal resonant unit structure is disposed on the lower surface of the dielectric substrate. The first and second metal resonant unit structures are connected through metal vias on the dielectric substrate. This structure can solve the problem that radar sidelobe blanking technology cannot simultaneously reduce radar sidelobes and avoid introducing redundant additional interference sources.

Description

Technical Field

[0001] This invention belongs to the field of low sidelobe antenna technology and relates to a dual-polarization angle-selective surface structure for reducing radar sidelobes. Background Technology

[0002] In modern radar systems, electronic countermeasures play an increasingly important role in modern warfare. Radars without anti-jamming technology completely lose their ability to detect and determine enemy targets. To improve radar detection capabilities and target parameter measurement accuracy, it is usually necessary to reduce the sidelobes of the antenna array to improve the sensitivity of the reconnaissance receiver. Currently, the main technologies for reducing radar sidelobes include sidelobe cancellation and sidelobe blanking. Sidelobe blanking suppresses sidelobe interference by adding several auxiliary antennas near the main antenna. The gain on the main lobe of the radar's main antenna is much greater than the gain of the auxiliary channels, and the signal strength received on the main lobe is much greater than that of the auxiliary channels. Furthermore, the gain in the auxiliary channels is greater than the sidelobe gain in all directions of the main antenna. Selective transmission is then used to suppress radar sidelobes, thereby improving the radar's anti-jamming capability.

[0003] Over the past few decades, manipulating and selecting electromagnetic waves has attracted widespread attention due to the three fundamental properties of electromagnetic waves: frequency, polarization, and propagation direction. Furthermore, angle-selective surfaces allow electromagnetic waves to propagate at certain incident angles while reflecting them at other angles. This has many attractive applications in optical and microwave systems, particularly in effectively suppressing or reducing sidelobes of antenna arrays, which could improve the detection accuracy of radar systems and the performance of communication systems. The ability to manipulate the incident angle of light has long been a scientific challenge in optics. Although angle selectivity has been largely achieved, the size of angle-selective surface systems increases dramatically when operating frequencies shift from optical to microwave systems, and the anisotropic dielectric materials used to satisfy Brewster's angle principle become difficult to meet requirements for use in the microwave band. It is well known that the resonant frequency of a frequency-selective surface shifts at different incident angles. Based on this phenomenon, angle selectivity can be achieved at a fixed operating frequency.

[0004] In summary, as radar systems place increasing demands on low-sidelobe antenna technology, while existing sidelobe blanking techniques can suppress radar sidelobe interference, they often introduce redundant active structures and additional interference sources. Therefore, dual-polarization angle-selective surface structures that can simultaneously reduce radar sidelobes and maintain polarization stability have significant application value. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a dual-polarization angle-selective surface structure for reducing radar sidelobes. This structure can solve the problem that radar sidelobe blanking technology cannot simultaneously reduce radar sidelobes and avoid introducing redundant additional interference sources.

[0006] To achieve the above objectives, this invention discloses a dual-polarization angle-selective surface structure for reducing radar sidelobes, comprising an upper structure and a lower structure, with an air gap between the upper and lower structures; both the upper and lower structures include a plurality of frequency-selective surface units arranged in an array, wherein each frequency-selective surface unit includes a dielectric substrate, a first metal resonant unit structure is disposed on the upper surface of the dielectric substrate, and a second metal resonant unit structure is disposed on the lower surface of the dielectric substrate, the first metal resonant unit structure and the second metal resonant unit structure being connected through metal vias on the dielectric substrate.

[0007] The thickness of the air gap is A rectangular air gap is used, where λ is the wavelength of the operating frequency band.

[0008] The dielectric substrate is a square plate with a relative permittivity of 2.0 to 4.0.

[0009] The side length of the dielectric substrate is L = 14.0 mm to 15.0 mm, and the thickness of the dielectric substrate is t = 0.4 mm to 1.0 mm.

[0010] Both the first metal resonant unit structure and the second metal resonant unit structure include a rectangular metal ring and a cross-shaped structure disposed on a dielectric substrate, wherein the cross-shaped structure is located inside the rectangular metal ring.

[0011] The diagonal of the dielectric substrate, the diagonal of the rectangular metal ring, and the cross-shaped structure coincide.

[0012] The rectangular metal ring has a line width w = 0.5mm to 1.0mm and a side length L = 14.0mm to 15.0mm.

[0013] The line width of the cross-shaped structure is m = 0.8mm to 1.2mm, and the arm length is p = 10.0mm to 14.0mm.

[0014] The diameter of the metal via is D = 0.8mm to 1.2mm.

[0015] The metal vias are located at the center of the dielectric substrate, the center of the cross-shaped structure, and the center of the rectangular metal ring.

[0016] The present invention has the following beneficial effects:

[0017] In practical operation, the dual-polarization angle-selective surface structure for reducing radar sidelobes described in this invention, when a plane wave is incident in the yoz plane at an arbitrary incident angle (θ) relative to the -z direction, the electric field of TE polarization is along the x-axis, and the magnetic field of TM polarization is along the y-axis. The so-called dual-polarization angle-selective surface can be described as having high transmission rate under normal incidence and high reflectivity for both polarizations under oblique incidence. Since the frequency-selective surface array structure with thickness t has an equivalent circuit model that can be approximately equivalent to a normalized susceptance, the invention firstly achieves significantly varying susceptance values ​​under different incident angles (θ) by designing the frequency-selective surface unit structure. Secondly, to achieve high transmission rate characteristics for the designed frequency-selective surface array under normal incidence, this invention constructs an equivalent circuit model of the same two-layer frequency-selective surface array structure to calculate the bandpass condition of the designed dual-polarization angle-selective surface. The thickness of the air gap between the two layers of the frequency-selective surface array is... By employing a rectangular air gap, where λ is the wavelength of the operating frequency band, a dual-polarization angle selectivity characteristic is ultimately achieved. Since the profile height of the designed dual-polarization angle selectivity surface is approximately 0.5λ, and the frequency selectivity surface structure used is a passive structure, this low radar sidelobe antenna technology can simultaneously reduce radar sidelobes and polarization stability characteristics without introducing redundant active structures or additional interference sources. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of the present invention;

[0020] Figure 3 This is a schematic diagram of the structure of the metal resonant unit in this invention;

[0021] Figure 4 This is a side view of the structure of the present invention;

[0022] Figure 5 This is a graph showing the transmission coefficient of the incident wave at different incident angles in TE polarization mode according to the present invention.

[0023] Figure 6 This is a graph showing the transmission coefficient of the incident wave at different incident angles in TM polarization mode according to the present invention.

[0024] Figure 7 The graph shows the angle selection performance of the present invention in TE polarization mode and TM polarization mode.

[0025] Among them, 1 is a rectangular metal ring, 2 is a cross structure, 3 is a metal via, 4 is an air gap, and 5 is a dielectric substrate. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0027] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0028] refer to Figures 1 to 3 The dual-polarization angle selective surface structure for reducing radar sidelobes described in this invention includes an upper structure and a lower structure, with an air gap between them. Both the upper and lower structures include a plurality of frequency selective surface units arranged in an array. Each frequency selective surface unit includes a dielectric substrate. A first metal resonant unit structure is disposed on the upper surface of the dielectric substrate, and a second metal resonant unit structure is disposed on the lower surface of the dielectric substrate. The first and second metal resonant unit structures are connected through metal vias on the dielectric substrate.

[0029] In this embodiment, the thickness of the air gap is A rectangular air gap is used, where λ is the wavelength of the operating frequency band.

[0030] In this embodiment, the dielectric substrate is a square plate with a relative permittivity of 2.0 to 4.0; the side length of the dielectric substrate is L = 14.0 mm to 15.0 mm, and the thickness of the dielectric substrate is t = 0.4 mm to 1.0 mm.

[0031] In this embodiment, both the first metal resonant unit structure and the second metal resonant unit structure include a rectangular metal ring and a cross-shaped structure disposed on a dielectric substrate, wherein the cross-shaped structure is located inside the rectangular metal ring.

[0032] In this embodiment, the diagonal of the dielectric substrate, the diagonal of the rectangular metal ring, and the cross-shaped structure coincide; the metal via is located at the center of the dielectric substrate, the center of the cross-shaped structure, and the center of the rectangular metal ring.

[0033] In this embodiment, the line width w of the rectangular metal ring is 0.5mm to 1.0mm, and the side length is L = 14.0mm to 15.0mm.

[0034] In this embodiment, the line width of the cross-shaped structure is m = 0.8mm to 1.2mm, and the arm length is p = 10.0mm to 14.0mm.

[0035] In this embodiment, the diameter D of the metal via is 0.8 mm to 1.2 mm.

[0036] Example 1

[0037] In this embodiment, both the upper and lower structures include nine frequency selective surface units arranged in an array.

[0038] The dielectric substrate is a square plate with a relative permittivity of 2.2, h = 18 mm; L = 14.6 mm; t = 0.8 mm; w = 0.7 mm; L = 14.6 mm; m = 1.0 mm; p = 12.0 mm; D = 1.0 mm.

[0039] Example 2

[0040] The difference between this embodiment and Embodiment 1 is that h = 33 mm.

[0041] Example 2

[0042] The difference between this embodiment and Embodiment 1 is that the dielectric substrate 5 is a square plate with a relative permittivity of 4.8, L = 14.0 mm, t = 0.4 mm, w = 1.0 mm, m = 0.8 mm, p = 13.0 mm, and D = 0.8 mm.

[0043] Simulation Experiment

[0044] The specific content of this experiment is as follows:

[0045] The transmission coefficient of the dual-polarization angle-selective surface structure in Embodiment 1 above under different incident angles in TE polarization mode was simulated and calculated using the commercial electromagnetic simulation software CST Studio Suite-2021 of the time-domain finite element method. The results are as follows: Figure 5 As shown.

[0046] The transmission coefficient of the dual-polarization angle-selective surface in Embodiment 1 above under different incident angles in TM polarization mode was simulated and calculated using the commercial electromagnetic simulation software CST Studio Suite-2021 of the time-domain finite element method. The results are as follows: Figure 6 As shown.

[0047] The angle selection performance of the dual-polarization angle-selective surface in Embodiment 1 above under TE and TM polarization modes was simulated and calculated using the commercial electromagnetic simulation software CST Studio Suite-2021, a time-domain finite element method. The results are as follows: Figure 7 As shown.

[0048] refer to Figure 5 The horizontal axis represents frequency, and the vertical axis represents transmission coefficient. As can be seen from the simulation results, the transmission coefficient characteristic curve of this structure is around 10GHz in the operating frequency band. When the incident angle θ of the TE-polarized electromagnetic wave is around 0°, the transmission coefficient varies from 0dB to -1dB, realizing the bandpass characteristic. When the incident angle θ of the TE-polarized electromagnetic wave is ≥20°, the transmission coefficient varies from -15dB to -50dB, realizing the bandstop characteristic. This shows that the present invention has good angle selectivity characteristics.

[0049] refer to Figure 6 The horizontal axis represents frequency, and the vertical axis represents transmission coefficient. As can be seen from the simulation results, the transmission coefficient characteristic curve of this structure is around 10GHz in the operating frequency band. When the incident angle θ of the TM-polarized electromagnetic wave is around 0°, the transmission coefficient varies from 0dB to -1dB, realizing the bandpass characteristic. When the incident angle θ of the TM-polarized electromagnetic wave is ≥20°, the transmission coefficient varies from -15dB to -60dB, realizing the bandstop characteristic. This shows that the present invention has the angle selectivity characteristic of dual polarization.

[0050] refer to Figure 7 The horizontal axis represents the incident angle of the electromagnetic wave, 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 10 GHz, the bandpass characteristic changes from 0 dB to -1 dB within the incident angle range of -15° to +15°, while the bandstop characteristic changes from -20 dB to -50 dB within the incident angle ranges of -25° to -85° and +25° to +85°. Furthermore, it exhibits good angular selectivity in both vertical and horizontal polarization directions, ensuring dual-polarization angular selectivity while simultaneously meeting the requirements of low profile and no introduction of additional interference sources.

[0051] It should be noted that the present invention has the following characteristics:

[0052] This invention achieves a bandpass characteristic that varies from 0 dB to -1 dB within an electromagnetic wave incident angle range of -15° to +15°, and a bandstop characteristic that varies from -20 dB to -50 dB within incident angle ranges of -25° to -85° and +25° to +85°, while also exhibiting good angular selectivity in both vertical and horizontal polarization directions.

[0053] This invention can achieve good angular selectivity in both vertical and horizontal polarization directions, and different operating frequency bands can be achieved by adjusting the structural dimensions, thus expanding the application range.

[0054] This invention is based on a frequency-selective surface with a passive structure.

[0055] This invention features small size and low profile, with unit structure size of 14.6mm × 14.6mm and unit spacing of 0mm. The dual polarization angle is selected with a surface thickness of 0.8mm (0.5λ).

[0056] Compared with radar sidelobe blanking technology, the present invention has a simple system structure, does not introduce redundant active structures, reduces radar sidelobes without introducing additional interference sources, and has a low dual-polarization angle selection surface profile and low cost.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A dual-polarization angle selective surface structure for reducing radar sidelobes, characterized in that, It includes an upper structure and a lower structure, with an air gap between them; both the upper and lower structures include a plurality of frequency selective surface units arranged in an array, wherein each frequency selective surface unit includes a dielectric substrate, a first metal resonant unit structure is provided on the upper surface of the dielectric substrate, and a second metal resonant unit structure is provided on the lower surface of the dielectric substrate, and the first metal resonant unit structure and the second metal resonant unit structure are connected through metal vias on the dielectric substrate; The thickness of the air gap is , ...using a rectangular air gap, The wavelength of the operating frequency band; Both the first metal resonant unit structure and the second metal resonant unit structure include a rectangular metal ring and a cross-shaped structure disposed on a dielectric substrate, wherein the cross-shaped structure is located inside the rectangular metal ring; The diagonal of the dielectric substrate, the diagonal of the rectangular metal ring, and the cross-shaped structure coincide.

2. The dual-polarization angle selective surface structure for reducing radar sidelobes according to claim 1, characterized in that, The dielectric substrate is a square plate with a relative permittivity of 2.0 to 4.

0.

3. The dual-polarization angle selective surface structure for reducing radar sidelobes according to claim 1, characterized in that, The side length of the dielectric substrate is L = 14.0 mm ~ 15.0 mm, the thickness of the dielectric substrate is t = 0.4 mm ~ 1.0 mm.

4. The dual-polarization angle selective surface structure for reducing radar sidelobes according to claim 1, characterized in that, Line width of rectangular metal ring w = 0.5 mm ~ 1.0 mm, side length is L = 14.0 mm ~ 15.0 mm.

5. The dual-polarization angle selective surface structure for reducing radar sidelobes according to claim 1, characterized in that, The line width of the cross-shaped structure is m = 0.8 mm ~ 1.2 mm, arm length is p = 10.0 mm ~ 14.0 mm.

6. The dual-polarization angle selective surface structure for reducing radar sidelobes according to claim 4, characterized in that, The metal vias are located at the center of the dielectric substrate, the center of the cross-shaped structure, and the center of the rectangular metal ring.

7. The dual-polarization angle selective surface structure for reducing radar sidelobes according to claim 1, characterized in that, Diameter of metal via D = 0.8 mm ~ 1.2 mm.

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