Dual-layer cooperative coupling based absorbing and transmitting integrated frequency selective absorber and application

Abstract

This invention provides a frequency-selective absorber based on dual-layer synergistic coupling and its application, belonging to the field of functional materials technology. The structure includes a loss layer and a bandpass frequency-selective surface layer, with an air layer between the two layers. The loss layer includes a first dielectric substrate and first and second metal patches with I-shaped derivative patterns on its upper and lower surfaces, each with a resistor loaded on it. The bandpass frequency-selective surface layer includes a second dielectric substrate and a third cross-shaped slotted metal patch on its upper surface. This invention achieves broadband absorption in the absorption band and low insertion loss transmission in the transmission band through the synergistic coupling of the loss layer and the bandpass layer. When this structure is placed above an antenna, it can effectively reduce the radar cross-section of the antenna system while ensuring antenna radiation performance. This structure has advantages such as wide absorption bandwidth, low transmission insertion loss, and good angular stability, making it suitable for radar stealth and electromagnetic compatibility applications.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, specifically relating to a frequency selective absorber based on dual-layer synergistic coupling and its application. Background Technology

[0002] With the continuous development of radar detection technology, military platforms are placing higher demands on the stealth performance of radomes. Integrated penetration-absorbing frequency selective surfaces can achieve low-loss transmission within the antenna's operating frequency band, while simultaneously achieving efficient absorption in out-of-band frequencies, effectively reducing the radar cross-section of bistatic and multistatic radar cross-sections, thus becoming a research hotspot in the field of electromagnetic stealth.

[0003] Existing integrated penetration-absorbing frequency selective absorbers can be functionally categorized into three types: wave-transmitting-absorbing, wave-absorbing-transmitting, and wave-absorbing-transmitting-absorbing. However, existing integrated penetration-absorbing frequency selective absorbers generally suffer from narrow absorption bandwidth. Research shows that single-layer absorbers can only generate a single operating frequency band, and their relative bandwidth is usually difficult to exceed 50%, which cannot meet the stealth requirements of ultra-wideband radar systems. Current designs for integrated penetration-absorbing electromagnetic structures mainly focus on the S, C, and X bands, making them unable to meet the growing demands of high-frequency bands. Therefore, researching low-scattering wave-transmitting structures in the Ku-band has urgent practical significance.

[0004] Currently, most publicly designed low-scattering transmission structures are concentrated in the S, C, and X bands, making it difficult to cover the higher-frequency Ku band. They also suffer from drawbacks such as large element size, narrow transmission bandwidth, excessive insertion loss, and narrow low-scattering bandwidth. This not only increases manufacturing costs but also limits their application in multi-band satellite communications and other fields. Therefore, designing and fabricating a low-scattering absorption-transmission integrated structure that operates in the S-Ku ultra-wideband range and possesses excellent angular stability, low profile thickness, small element size, low insertion loss, and wide bandwidth is a key focus in this field. Summary of the Invention

[0005] The purpose of this invention is to address the problems of narrow absorption bandwidth, large transmission insertion loss, and insufficient RCS reduction performance in the prior art by providing a frequency selective absorber based on dual-layer synergistic coupling. Through differentiated design of the loss layer and interlayer coupling control, it achieves synergistic optimization of broadband absorption and low insertion loss transmission, and significantly improves the RCS reduction effect of the antenna system.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A dual-layer synergistic coupling integrated penetration-selective frequency absorber includes a loss layer and a bandpass frequency selective surface layer, with an air layer between the loss layer and the bandpass frequency selective surface layer. The loss layer includes a loss layer dielectric substrate, an upper loss layer metal patch 3 disposed on the upper surface 1 of the loss layer dielectric substrate, and a lower loss layer metal patch 6 disposed on the lower surface 4 of the loss layer dielectric substrate. Lumped resistors are loaded on both the upper loss layer metal patch 3 and the lower loss layer metal patch 6. The bandpass frequency selective surface layer includes a bandpass frequency selective surface layer dielectric substrate 7 and a bandpass frequency selective surface layer metal patch 8 disposed on the upper surface of the bandpass frequency selective surface layer dielectric substrate 7.

[0008] The upper metal patch 3 and the lower metal patch 6 of the loss layer each include two I-shaped metal patterns. Each I-shaped metal pattern includes a horizontal metal arm and a vertical metal arm disposed in the middle of the horizontal metal arm. A single-piece resistor is loaded on each vertical metal arm. The direction of the connection between the two single-piece resistors of the two I-shaped metal patterns is vertical, and the direction perpendicular to the connection is horizontal.

[0009] The bandpass frequency selection surface layer metal patch 8 has a cross-shaped slotted metal pattern, which includes a square metal patch and a cross-shaped slit in the center of the square metal patch.

[0010] As a preferred embodiment, the thickness of the upper metal patch 3, the lower metal patch 6, and the bandpass frequency selection surface metal patch 8 is all 0.035 mm, and the resistance of the chip resistor is 125 Ω.

[0011] As a preferred embodiment, the material of the loss layer dielectric substrate has a relative permittivity of 3.48, a loss tangent of 0.0037, and a thickness of 0.25 mm; the material of the bandpass frequency selection surface layer dielectric substrate 7 has a relative permittivity of 2.2, a loss tangent of 0.0009, and a thickness of 0.5 mm.

[0012] As a preferred embodiment, the cell period of the loss layer and the bandpass frequency selection surface layer is 12 mm, and the thickness of the air layer is 5 mm.

[0013] As a preferred embodiment, the materials of the upper metal patch 3, the lower metal patch 6, and the bandpass frequency selection surface metal patch 8 are selected from copper, aluminum, gold, and silver.

[0014] As a preferred embodiment, the air layer material is selected from one of the following: polymethacrylamide foam, polyimide foam, polyurethane foam, polyvinyl chloride foam, phenolic foam, polyethylene foam, and polyethylene terephthalate.

[0015] The second objective of this invention is to provide an application of the aforementioned dual-layer cooperative coupling integrated frequency selective absorber in selective absorption and transmission, and in antenna window operation. When used as a radar radome, this structure can achieve "high in-band transmission and wide out-of-band absorption," significantly improving radar stealth capabilities while ensuring normal antenna performance. It can also be used in civilian electromagnetic compatibility scenarios to reduce out-of-band interference and effectively reduce the radar cross-section of the antenna system while ensuring antenna radiation performance.

[0016] The beneficial effects of this invention are as follows:

[0017] Full-wave electromagnetic simulation verified that the designed frequency-selective absorber based on dual-layer cooperative coupling exhibits high transmission efficiency with an insertion loss of only 0.75 dB at 15.01 GHz in the transmission passband. 21 The transmission bandwidth of > -1 dB covers 14.51 GHz to 15.55 GHz. In the absorbing band, S 11 The bandwidth of < -10 dB covers 7.03 GHz to 15.66 GHz, with an absolute bandwidth of 8.63 GHz and a relative bandwidth of 76.07%. This result verifies the effectiveness of the proposed design method and the dual-layer synergistic coupling integrated absorption and transmission frequency selective absorber in achieving broadband absorption and high-frequency transmission in an integrated manner. 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 upper layer of the loss layer in this invention;

[0020] Figure 3 This is a schematic diagram of the structure of the lower layer of the loss layer in this invention;

[0021] Figure 4 This is a schematic diagram of the upper layer of the bandpass frequency selective surface layer of the present invention.

[0022] Figure 5 This is a schematic diagram showing the parameters of the upper metal patch and the lower metal patch of the loss layer in this invention.

[0023] Figure 6 This is a schematic diagram of the parameters of the bandpass frequency selective surface layer metal patch of the present invention.

[0024] Figure 7 This is the S under TE and TM polarization in Embodiment 1 of the present invention. 11 S 21 Absorption rate curve variation graph.

[0025] Figure 8This is a graph showing the change in absorption rate curves under TE and TM polarization in Embodiment 1 of the present invention.

[0026] Figure 9 This is a graph showing the RCS reduction curve of the FSR for a 15 GHz waveguide slot antenna array under HH and VV polarizations in Embodiment 1 of the present invention.

[0027] Layer Ⅰ - Loss layer, Layer Ⅱ - Bandpass frequency selective surface layer.

[0028] 1- Upper surface of the dielectric substrate of the loss layer; 2- Upper resistor of the loss layer; 3- Upper metal patch of the loss layer; 4- Lower surface of the dielectric substrate of the loss layer; 5- Lower resistor of the loss layer; 6- Lower metal patch of the loss layer.

[0029] 7 - Bandpass frequency selection surface layer dielectric substrate, 8 - Bandpass frequency selection surface layer metal patch. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0031] Example 1

[0032] like Figures 1-3 As shown, an embodiment provides a dual-layer co-coupling integrated penetration-selective frequency absorber, including a loss layer and a bandpass frequency selective surface layer. An air layer is disposed between the loss layer and the bandpass frequency selective surface layer. The loss layer includes a loss layer dielectric substrate, an upper loss layer metal patch 3 disposed on the upper surface 1 of the loss layer dielectric substrate, and a lower loss layer metal patch 6 disposed on the lower surface 4 of the loss layer dielectric substrate. Lumped resistors are loaded on both the upper loss layer metal patch 3 and the lower loss layer metal patch 6. The bandpass frequency selective surface layer includes a bandpass frequency selective surface layer dielectric substrate 7 and a bandpass frequency selective surface layer metal patch 8 disposed on the upper surface of the bandpass frequency selective surface layer dielectric substrate 7.

[0033] The upper metal patch 3 and the lower metal patch 6 of the loss layer each include two I-shaped metal patterns. Each I-shaped metal pattern includes a horizontal metal arm and a vertical metal arm disposed in the middle of the horizontal metal arm. A single-piece resistor is loaded on each vertical metal arm. The direction of the connection between the two single-piece resistors of the two I-shaped metal patterns is vertical, and the direction perpendicular to the connection is horizontal.

[0034] like Figure 4 As shown, the bandpass frequency selection surface layer metal patch 8 is a cross-shaped slotted metal pattern. The cross-shaped slotted metal pattern includes a square metal patch and a cross-shaped slit opened in the center of the square metal patch. The double-layer cross-shaped slotted structure forms a second-order bandpass response through the electromagnetic coupling of the air layer, generating two transmission poles in the transmission frequency band, widening the transmission bandwidth and reducing insertion loss.

[0035] Preferably, the thickness of the upper metal patch 3, the lower metal patch 6, and the bandpass frequency selection surface metal patch 8 is all 0.035 mm, and the resistance of the chip resistor is 125Ω.

[0036] Preferably, the material of the loss layer dielectric substrate has a relative permittivity of 3.48, a loss tangent of 0.0037, and a thickness of 0.25 mm; the material of the bandpass frequency selection surface layer dielectric substrate 7 has a relative permittivity of 2.2, a loss tangent of 0.0009, and a thickness of 0.5 mm.

[0037] Preferably, the cell period of the loss layer and the bandpass frequency selection surface layer is 12 mm, and the thickness of the air layer is 5 mm.

[0038] Preferably, the materials of the upper metal patch 3, the lower metal patch 6, and the bandpass frequency selection surface metal patch 8 are selected from copper, aluminum, gold, and silver.

[0039] Preferably, the air layer material is selected from one of polymethacrylamide foam, polyimide foam, polyurethane foam, polyvinyl chloride foam, phenolic foam, polyethylene foam, and polyethylene terephthalate.

[0040] The embodiment also provides an application of the aforementioned dual-layer cooperative coupling integrated frequency selective absorber in selective absorption and transmission and antenna window operation. When used as a radar radome, this structure can achieve "high in-band transmission and wide out-of-band absorption," significantly improving radar stealth capabilities while ensuring normal antenna performance. It can also be used in civilian electromagnetic compatibility scenarios to reduce out-of-band interference and effectively reduce the radar cross-section of the antenna system while ensuring antenna radiation performance.

[0041] like Figure 5 Figure 6 As shown, the remaining detailed structural parameters of the integrated transmission-selective absorber based on dual-layer cooperative coupling in this embodiment are as follows:

[0042] Parameter Value Parameter Value p 12 mm <![CDATA[l0]]> 0.2 mm w 2.4 mm l 9.4 mm <![CDATA[w1]]> 0.1 mm <![CDATA[l1]]> 1.5 mm <![CDATA[w2]]> 0.1 mm <![CDATA[l2]]> 2.3 mm t 2.4 mm

[0043] The key technology of this solution lies in the following: a dual-layer synergistic coupling integrated transmission-selective frequency absorber is proposed. This structure includes a loss layer and a bandpass frequency selective surface layer, with an air layer between the loss layer and the bandpass frequency selective surface layer. The loss layer includes a loss layer dielectric substrate, an upper loss layer metal patch 3 disposed on the upper surface 1 of the loss layer dielectric substrate, and a lower loss layer metal patch 6 disposed on the lower surface 4 of the loss layer dielectric substrate. Both the upper loss layer metal patch 3 and the lower loss layer metal patch 6 are loaded with lumped resistors. The bandpass frequency selective surface layer includes a bandpass frequency selective surface layer dielectric substrate 7 and a bandpass frequency selective surface layer metal patch 8 disposed on the upper surface of the bandpass frequency selective surface layer dielectric substrate 7. Both the upper loss layer metal patch 3 and the lower loss layer metal patch 6 are I-shaped derived metal patterns, while the bandpass frequency selective surface layer metal patch 8 is a cross-shaped slotted metal pattern. The loss layer and the bandpass layer together achieve low insertion loss transmission and high selective filtering.

[0044] like Figure 7 As shown, taking the TE polarization mode as an example, this structure exhibits a very high transmission efficiency with an insertion loss of only 0.75 dB at 15.01 GHz in the transmission passband; S 21 The transmission bandwidth of > -1 dB covers 14.51 GHz to 15.55 GHz. In the absorbing band, S 11 The bandwidth of < -10 dB covers 7.03 GHz to 15.66 GHz, with an absolute bandwidth of 8.63 GHz and a relative bandwidth of 76.07%.

[0045] like Figure 8 As shown, the absorption rate remains good at 45° as the angle increases, demonstrating good angular stability.

[0046] like Figure 9 As shown, when this structure is placed above an antenna array operating at a frequency of 15 GHz, it can significantly reduce the radar cross-section of the antenna system in the S to Ku bands, while ensuring the radiation performance within the antenna's operating frequency band.

[0047] Example 2

[0048] This embodiment provides a method for fabricating a frequency-selective absorber based on dual-layer synergistic coupling, comprising the following steps:

[0049] ① The material of the loss layer dielectric substrate is Rogers RO4350B, with a relative permittivity of 3.48, a loss tangent of 0.0037, and a thickness of 0.25 mm; the material of the bandpass frequency selective surface layer dielectric substrate 7 is F4B220, with a relative permittivity of 2.2, a loss tangent of 0.0009, and a thickness of 0.5 mm. A lead-tin resist layer is pre-plated on the substrate using printed circuit board technology, and then the remaining copper foil without the pre-plated lead-tin resist layer is etched away chemically. Upper loss layer metal patch 3 and lower loss layer metal patch 6 are respectively prepared on the upper and lower sides of the loss layer dielectric substrate, and a bandpass frequency selective surface layer metal patch 8 is prepared above the bandpass frequency selective surface layer dielectric substrate 7.

[0050] ② The chip resistor is soldered to a designated position on the integrated frequency selective absorber based on dual-layer synergistic coupling using a soldering method;

[0051] ③ PMI foam with a dielectric constant of 1.06 and a loss tangent of 0.0037 was selected as the air layer material, with a thickness of 5.00 mm. The layers were bonded together sequentially using epoxy resin to form a whole.

[0052] ④ Finally, through cutting and reshaping, a frequency selective absorber based on dual-layer synergistic coupling with an area of ​​300 mm × 300 mm was obtained.

[0053] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A frequency-selective absorber based on dual-layer synergistic coupling, characterized in that: The system includes a loss layer and a bandpass frequency selective surface layer, with an air layer between the loss layer and the bandpass frequency selective surface layer. The loss layer includes a loss layer dielectric substrate, an upper loss layer metal patch (3) disposed on the upper surface (1) of the loss layer dielectric substrate, and a lower loss layer metal patch (6) disposed on the lower surface (4) of the loss layer dielectric substrate. Both the upper loss layer metal patch (3) and the lower loss layer metal patch (6) are loaded with lumped resistors. The bandpass frequency selective surface layer includes a bandpass frequency selective surface layer dielectric substrate (7) and a bandpass frequency selective surface layer metal patch (8) disposed on the upper surface of the bandpass frequency selective surface layer dielectric substrate (7). The upper metal patch (3) and the lower metal patch (6) of the loss layer each include two I-shaped metal patterns. Each I-shaped metal pattern includes a horizontal metal arm and a vertical metal arm disposed in the middle of the horizontal metal arm. Each vertical metal arm is loaded with a single-piece resistor. The direction of the connection between the two single-piece resistors of the two I-shaped metal patterns is vertical, and the direction perpendicular to the connection is horizontal. The bandpass frequency selection surface metal patch (8) is a cross-shaped slotted metal pattern, which includes a square metal patch and a cross-shaped slit in the center of the square metal patch.

2. The frequency-selective absorber based on dual-layer synergistic coupling according to claim 1, characterized in that: The thickness of the upper metal patch (3), the lower metal patch (6), and the bandpass frequency selection surface metal patch (8) is 0.035 mm, and the resistance of the chip resistor is 125Ω.

3. The frequency-selective absorber based on dual-layer synergistic coupling according to claim 1, characterized in that: The relative permittivity of the material of the loss layer dielectric substrate is 3.48, the loss tangent is 0.0037, and the thickness is 0.25 mm; the relative permittivity of the material of the bandpass frequency selection surface layer dielectric substrate (7) is 2.2, the loss tangent is 0.0009, and the thickness is 0.5 mm.

4. The frequency-selective absorber based on dual-layer synergistic coupling according to claim 1, characterized in that: The unit period of the loss layer and the bandpass frequency selection surface layer is 12 mm, and the thickness of the air layer is 5 mm.

5. The frequency-selective absorber based on dual-layer synergistic coupling according to claim 1, characterized in that: The upper metal patch of the loss layer (3), the lower metal patch of the loss layer (6), and the metal patch of the bandpass frequency selection surface layer (8) are selected from copper, aluminum, gold, and silver.

6. The frequency-selective absorber based on dual-layer synergistic coupling according to claim 1, characterized in that: The air layer material is selected from one of the following: polymethacrylamide foam, polyimide foam, polyurethane foam, polyvinyl chloride foam, phenolic foam, polyethylene foam, and polyethylene terephthalate.

7. The application of the frequency selective absorber based on dual-layer cooperative coupling as described in any one of claims 1 to 6 in selective absorption and transmission and antenna window operation.

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