Low RCS F-P resonant cavity antenna based on lossy metasurface and AMC structure

Abstract

The invention provides a low RCS F-P resonant cavity antenna based on a lossy metasurface and an AMC structure. The low RCS F-P resonant cavity antenna comprises an absorption type partial reflection surface structure located on the upper portion and a feed source antenna structure located on the lower portion. The absorption type partial reflection surface structure comprises a lossy metasurface layer, a metal patch common ground layer and a metal patch AMC1 layer which are separated by a first dielectric substrate layer and a second dielectric substrate layer; the feed source antenna structure comprises an antenna patch layer, a metal floor layer, a coaxial structure and a third dielectric substrate layer, the antenna patch layer and the metal floor layer are oppositely arranged on the third dielectric substrate layer, and the coaxial structure is connected between the antenna patch layer and the metal floor layer. According to the invention, a method for analyzing the wave absorption and reflection performance of the two ports of the PRS structure unit is adopted, the process of integrated design of the low-RCS, high-directivity and high-gain F-P antenna is simplified, the overall profile of the antenna is effectively reduced, and the antenna is easier to be integrated with other radio frequency devices for use.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to a low RCS FP resonant cavity antenna based on a lossy metasurface and an AMC structure. Background Technology

[0002] Antennas are crucial components of electronic systems such as radar, communication, and navigation, directly impacting the effectiveness and combat capabilities of military electronic systems. Minimizing the radar cross-section (RCS) without compromising antenna performance is essential for enhancing the survivability and penetration capabilities of combat systems. Due to limitations imposed by antenna performance, the design freedom of general military antennas is limited, making it difficult to reduce radar echo through shape optimization. The introduction of lossy components and the loading of absorbing materials inevitably affect the antenna's ability to radiate / receive electromagnetic waves. Furthermore, using stealth radomes cannot achieve in-band RCS reduction, hindering radar stealth within the antenna's operating frequency band. Therefore, balancing the radiation and scattering characteristics within the antenna's operating frequency band is paramount in low-RCS antenna design. In addition, due to space constraints and stringent stealth requirements in military equipment, low-profile design and increased reduction in size are also crucial for low-RCS antennas.

[0003] In 1956, American scientist G.T. Vrentini innovatively extended the Fabry-Perot resonant cavity theory to the field of antennas for the first time. Using a waveguide horn as a feed source, a partially reflective surface made of metal mesh was placed above the waveguide horn opening, so that it and the antenna floor formed an FP resonant cavity. After multiple reflections in it, the gain in the main radiation direction was significantly improved.

[0004] Due to the ease of integration, miniaturization, and diverse feeding methods of FP antennas, numerous studies have been conducted on low-RCS FP resonant antennas. In 2017, Lei Zhang et al. proposed a low-RCS FP resonant antenna based on a diffuse scattering structure. This work designed four partial reflection elements covering 270° of reflection phases, achieving diffuse reflection through a specific arrangement, thus realizing bistatic RCS reduction of the antenna. However, the reflection phase of the scattering element varies significantly with frequency, resulting in a narrow RCS reduction bandwidth of only 40%. In 2021, Weiliang Yu et al. proposed a low-RCS FP resonant antenna with lumped resistance. By loading an absorbing / transmission frequency selective surface above the feed antenna, out-of-band RCS reduction was achieved. However, due to the low in-band PRS reflection amplitude, the peak gain of this antenna was only 11.77 dBi. In 2022, You-Feng Cheng et al. proposed a low RCS FP resonant antenna based on spatial path difference. By reducing the area of ​​the PRS by half, a spatial path difference is constructed, resulting in a phase difference of approximately 180° between the electromagnetic waves reflected directly by the lower reflector of the resonant cavity and the PRS, achieving phase cancellation and reducing the RCS of the FP antenna. However, due to the reduction in the PRS area, the electromagnetic waves radiated from the feed cannot be effectively reflected, leading to a lower peak gain for the antenna. Furthermore, given a fixed antenna profile, the spatial path difference is significantly affected by frequency, resulting in a relatively low peak RCS reduction of only 20 dB. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a low RCS FP resonant cavity antenna based on a lossy metasurface and an AMC structure. The technical problem to be solved by this invention is achieved through the following technical solution:

[0006] A low RCS FP resonant cavity antenna based on a lossy metasurface and AMC structure includes: an absorptive partial reflective surface structure 1) located at the top and a feed antenna structure 2) located at the bottom;

[0007] The absorptive partial reflective surface structure 1 includes a lossy metasurface layer 11, a metal patch ground layer 12, a metal patch AMC1 layer 13, a first dielectric substrate layer 14, and a second dielectric substrate layer 15; the first dielectric substrate layer 14 is disposed between the lossy metasurface layer 11 and the metal patch ground layer 12, and the second dielectric substrate layer 15 is disposed between the metal patch ground layer 12 and the metal patch AMC1 layer 13;

[0008] The feed antenna structure 2 includes an antenna patch layer 21, a metal ground plane layer 22, a coaxial structure 23, and a third dielectric substrate layer 24. The antenna patch layer 21 and the metal ground plane layer 22 are both disposed on the third dielectric substrate layer 24 and are disposed opposite to each other. The coaxial structure 23 connects the antenna patch layer 21 and the metal ground plane layer 22.

[0009] Beneficial effects:

[0010] Compared with the prior art, the present invention has the following advantages:

[0011] 1. This invention adopts the form of FP resonant cavity antenna. The lower feed antenna structure serves as the feed and lower reflector of the resonant cavity, and the upper absorptive PRS layer serves as the upper reflector of the resonant cavity. The graphene periodic resistive patch on its surface achieves low RCS of the antenna. The AMC patch structure laid around the PRS layer and the feed antenna is used to construct the phase of the upper and lower reflectors in the FP antenna to achieve low profile design of the antenna.

[0012] 2. The microstrip antenna used in this invention simplifies the design of feed antennas. It uses the absorption rate to qualitatively analyze the effect of the absorbing PRS layer on the antenna radiation performance, including directivity, radiation efficiency and gain, which simplifies the overall FP antenna design. By reasonably adjusting the absorption and reflection performance of the two ports of the PRS unit, it simplifies the simultaneous realization of RCS reduction and high gain in the FP antenna design of the PRS structure. The proposed antenna can achieve RCS reduction in the range of 6-30 GHz, with a relative bandwidth of 133%.

[0013] 3. When optimizing the design of the PRS unit, the present invention uses frequency offset to make the resonant frequency of the PRS slightly higher than the antenna operating frequency, which further realizes the low absorption and strong reflection of the bottom radiating antenna by the PRS layer, improves the radiation efficiency, high directivity and high gain of the overall FP antenna structure, and the antenna peak gain can reach 15dBi.

[0014] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0015] Figure 1 A schematic diagram of a low RCS FP resonant cavity antenna based on a lossy metasurface and AMC structure is provided for an embodiment of the present invention;

[0016] Figure 2 A schematic diagram of a periodic unit cell of a partial reflective surface structure provided by the present invention;

[0017] Figure 3 This is a schematic diagram of the antenna patch layer in Example 1 provided by the present invention;

[0018] Figure 4This is a schematic diagram of the antenna patch layer in Example 2 provided by the present invention;

[0019] Figures 5 to 14 This is a schematic diagram of the simulation results provided by the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0021] The technical effects of the present invention will be illustrated below with examples.

[0022] The design concept of this invention is to reduce the broadband RCS of the antenna by using a lossy metasurface, to adjust the reflection phase of the upper and lower reflective surfaces of the FP resonant cavity using an AMC structure to reduce the cavity profile thickness, and to achieve broadband RCS reduction, low profile, and high gain of the FP antenna by using absorption qualitative analysis and resonant frequency shift.

[0023] refer to Figure 1 The present invention provides a low RCS FP resonant cavity antenna based on a lossy metasurface and an AMC structure, comprising: an absorptive partial reflective surface structure 1 located at the upper part and a feed antenna structure 2 located at the lower part;

[0024] The absorptive partial reflective surface structure 1 includes a lossy metasurface layer 11, a metal patch ground layer 12, a metal patch AMC1 layer 13, a first dielectric substrate layer 14, and a second dielectric substrate layer 15; the first dielectric substrate layer 14 is disposed between the lossy metasurface layer 11 and the metal patch ground layer 12, and the second dielectric substrate layer 15 is disposed between the metal patch ground layer 12 and the metal patch AMC1 layer 13.

[0025] The feed antenna structure 2 includes an antenna patch layer 21, a metal ground plane layer 22, a coaxial structure 23, and a third dielectric substrate layer 24. The antenna patch layer 21 and the metal ground plane layer 22 are both disposed on the third dielectric substrate layer 24 and are disposed opposite to each other. The coaxial structure 23 is connected between the antenna patch layer 21 and the metal ground plane layer 22.

[0026] refer to Figure 1 The lossy metasurface layer 11, the metal patch common ground layer 12, and the metal patch AMC1 layer 13 are composed of multiple units with the same period, and the period size of each unit ranges from 0.245λ. t ≤p1≤0.256λ t , λ t =c / f t , where λ t It is the antenna's operating center frequency f t The corresponding wavelength, c is the speed of light in a vacuum, f t It is the center frequency of the antenna's operation.

[0027] refer to Figure 2 Each unit of the lossy metasurface layer 11 is composed of a square thin film resistor 111; each unit of the metal patch ground layer 12 is composed of a first square metal patch 121; and each unit of the metal patch AMC1 layer 13 is composed of a second square metal patch 131.

[0028] Among them, the square thin-film resistor 111 is a graphene resistive film with a sheet resistance ranging from 30 Ohm / sq to 100 Ohm / sq, and its side length a1 ranging from 0.147λ. t ≤a1≤0.168λ t The side length a2 of the first square metal patch 121 ranges from 0.241λ. t ≤a2≤0.253λ t The side length a3 of the second square metal patch 131 ranges from 0.140λ. t ≤a3≤0.182λ t .

[0029] refer to Figure 3 The antenna patch layer 21 consists of a rectangular metal radiating patch 211 and a surrounding metal patch AMC2 structure 212; wherein the length l of the metal radiating patch 211 ranges from 0.280λ. t ≤l≤0.297λ t The width w ranges from 0.228λ. t ≤w≤0.238λ t The metal patch AMC2 structure 212 consists of periodically arranged third-dimensional metal patches, with the side length a4 of the third-dimensional metal patch ranging from 0.161λ. t ≤a4≤0.165λ t The spacing g between the three-dimensional metal patches ranges from 0.019λ. t ≤g≤0.021λ t .

[0030] The side length p of the metal floor layer 22 ranges from 2.450λ. t ≤p≤2.842λ t .

[0031] refer to Figure 3 The feed center of the coaxial structure 23 is located at a position offset by y1 along the y-axis from the geometric center of the metal radiating patch 211, with the offset distance y1 ranging from 0.046λ. t ≤y1≤0.067λ t Among them, the coaxial structure 23 adopts an inner conductor radius r i=0.3mm, outer conductor radius r o =1.05mm coaxial probe structure.

[0032] The first dielectric substrate layer 14 of the present invention uses a dielectric with a thickness of h2 = 2.5 mm and a dielectric constant of 2.65; the second dielectric substrate layer 15 uses a dielectric with a thickness of h3 = 2.5 mm and a dielectric constant of 2.65; and the third dielectric substrate layer 24 uses a dielectric with a thickness of h1 = 2.0 mm and a dielectric constant of 2.65.

[0033] Example 1:

[0034] Reference Figure 1 This embodiment includes an upper absorptive partial reflective surface (PRS) structure 1 and a lower feed antenna structure 2. The air cavity thickness between structure 1 and structure 2 is t = 4.8 mm. The absorptive partial reflective surface structure 1 is composed of a graphene resistive patch layer 11, a metal patch common ground layer 12, a metal patch AMC structure layer 13, and dielectric substrate layers 14 and 15 separating these three layers. The dielectric substrate is F4b material with a relative permittivity of 2.65 and a loss tangent of 0.0009. The feed antenna structure 2 is composed of an antenna patch layer 21, a metal ground plane layer 22, a coaxial structure 23, and a dielectric substrate layer 24. The metal radiating patch 211 and the metal ground plane layer 22 are connected by the coaxial structure 23 to form a patch antenna as the feed of the antenna. The metal ground plane layer 22 has a size of p = 70 mm, and the thickness of the third dielectric substrate layer 24 is h1 = 2 mm. The air cavity between structure 1 and structure 2 forms an FP resonant cavity, in which electromagnetic waves are continuously reflected to improve the gain of the bottom patch antenna.

[0035] Reference Figure 2 The PRS structure 1 has a unit period of p1 = 7 mm. A square thin-film resistor 111 is printed on the graphene resistive patch layer 11, with a unit size of a1 = 4.5 mm and a sheet resistance of 30 Ω / sq. A first square metal patch 121 is printed on the metal patch ground layer 12, with a unit size of a2 = 6.9 mm and made of lossy copper. A second square metal patch 131 is printed on the metal patch AMC1 structure layer 13, with a unit size of a3 = 5.2 mm and made of lossy copper. The thickness between the graphene resistive patch layer 11 and the metal patch ground layer 12 is h2 = 2.5 mm, and the thickness between the metal patch ground layer 12 and the metal patch AMC1 structure layer is h3 = 2.5 mm. The square thin-film resistor 111 can convert the incident electromagnetic wave energy into heat energy, thereby achieving RCS reduction. The size of the second square metal patch 131 affects the reflection performance of the metal patch AMC1 layer 13. The thickness of the FP antenna resonant cavity can be reduced by adjusting its unit size.

[0036] Reference Figure 3 The antenna patch layer 21 has a printed metal radiating patch 211 with dimensions w = 6.5 mm and l = 8 mm, made of lossy copper. The feed point of the coaxial structure 23 is located at a distance y1 = 1.9 mm from the geometric center of the metal radiating patch 211, and the radii of the inner and outer conductors of the coaxial structure are r. i =0.3mm, r o =1.05mm.

[0037] In this invention, the absorbing layer 11 of the absorptive partial reflective surface structure 1 can convert the incident electromagnetic wave into heat energy, thereby achieving broadband RCS reduction. The AMC layer 12 can achieve low absorption and strong reflection of the electromagnetic wave excited by the bottom feed patch antenna 2. The electromagnetic wave is continuously reflected and superimposed in the same direction in the cavity composed of structure 1 and structure 2, ultimately improving the gain and directivity of the FP antenna.

[0038] Example 2:

[0039] In this embodiment, the PRS structure 1 remains unchanged. An AMC2 metal patch 212 is added around the metal radiating patch 211 of the antenna patch layer 21. Furthermore, the following parameters are adjusted in this embodiment: the period of the structural unit of the PRS layer 1 is adjusted to p1 = 7.3 mm; the dimensions of the first square metal patch 121 and the second square metal patch 131 are adjusted to a2 = 7.2 mm and a3 = 4 mm, respectively. The thickness between the PRS structure 1 and the patch antenna structure 2 is t = 2.7 mm. The dimensions of the metal radiating patch 211 are adjusted to w = 6.8 mm and l = 8.5 mm; the dimensions of the metal ground plane layer 22 are adjusted to p = 81.2 mm; and the feed point position of the coaxial structure 23 is adjusted to y1 = 1.3 mm, while its coaxial inner and outer radii remain unchanged from Example 1.

[0040] Reference Figure 4 The dimensions of the AMC2 patch structure 212 added to the antenna patch layer 21 are: a4 = 4.7 mm, and the gap size is g = 0.55 mm.

[0041] The technical effectiveness of this example will be verified through simulation and experimentation below.

[0042] 1. Simulation conditions:

[0043] The absorption and reflection performance of the two ports of the PRS structure unit in Examples 1 and 2 of this invention, the reflection coefficient, gain, directivity and single-station RCS reduction performance of the FP antenna loaded with the PRS structure were simulated using the commercial simulation software HFSS_19.0. The upper and lower surfaces of the PRS structure unit correspond to port 1 and port 2 in the simulation, respectively.

[0044] 2. Simulation content and results:

[0045] Simulation 1 simulates the reflection phase and amplitude at the two ports and the absorption rate at both ports of Example 1 of this invention under periodic boundary conditions. Figure 5 As shown in Figure (a), the zero-phase frequency of the reflection at port 2 of the PRS structure unit is 10.4 GHz. The frequency range of the reflection phase within -90° to 90° is 8.6–12.4 GHz, with a relative bandwidth of 36.2%. The reflection amplitude within this frequency band varies from -1.8 to -0.2 dB. Figure 5 As shown in Figure (b), the absorption rates of electromagnetic waves incident from ports 1 and 2 of the PRS structural unit are as follows: for port 1, the peak absorption rates reach 78% and 82% at 13.2 GHz and 28 GHz, respectively, while for port 2, the peak absorption rate is only 5%. The high absorption rate of port 1 enables this absorptive PRS to achieve RCS reduction over a wide bandwidth, while the low absorption rate of port 2 results in weaker absorption of electromagnetic waves radiated by the bottom microstrip antenna, ensuring the high gain of the FP antenna.

[0046] Simulation 2 simulates the reflection coefficient of the FP antenna after applying PRS, based on Example 1 of this invention. Figure 6 It can be seen that after loading the PRS layer, the reflection coefficient is less than -10dB in the range of 10.1 to 10.9 GHz, indicating good impedance matching in this frequency band.

[0047] Simulation 3 simulates the efficiency and peak gain of the FP antenna after applying PRS, based on Example 1 of this invention. Figure 7 As shown, the loading of the PRS structure enables the antenna to achieve a maximum gain of 14.2 dBi.

[0048] Simulation 4: Simulate the radiation pattern of the FP antenna after loading PRS, based on Example 1 of the present invention. Figure 8 The radiation patterns of the antenna before and after loading a PRS at 10.3 GHz are given. It can be seen that the main radiation direction of the antenna remains in the direction of the antenna floor normal. After loading an absorptive PRS, the directivity of the antenna is significantly improved, with an improvement of 10 dB in the main radiation direction. The 3 dB wavenumber width in the E-plane and H-plane is 25.1°, and the sidelobe electrical average is less than 13.5 dB.

[0049] Simulation 5 simulates the single-site RCS reduction performance of the FP antenna after applying PRS, based on Example 1 of this invention. Figure 9 As shown, the antenna achieves RCS reduction in the 8GHz to 30GHz bandwidth, with the strongest RCS reduction performance at 12GHz and 29GHz, reaching 14.8dB and 15.2dB respectively.

[0050] Simulation 6 simulates the reflection phase and amplitude of the two ports of the PRS structural unit and the antenna patch layer 21, as well as the absorption rate of the two ports of the PRS layer 1 structural unit when electromagnetic waves are incident on them respectively, for Example 2 of the present invention. Figure 10 As shown in Figures (a) and (b), at 10.5 GHz, the reflection phase at the 2-port of the PRS structural unit is 92°, the reflection amplitude is -0.68 dB, and the reflection phase of the antenna patch layer 21 is 3°. The reduction in the sum of the reflection phases of the upper and lower reflective surfaces in the resonant cavity effectively reduces the thickness of the FP resonant cavity. Figure 11 It can be seen that the absorption rate of port 1 in the PRS structure unit is greater than 60% in the range of 11 to 27.5 GHz, and the absorption rate reaches a peak of 91% at 14 GHz. The absorption rate of port 2 reaches a peak of 3.7% at 11.5 GHz. The absorption resonant frequency is slightly higher than the antenna operating frequency, which further reduces the absorption rate at the antenna operating frequency to ensure the high gain of the FP antenna.

[0051] Simulation 7 simulates the reflection coefficient of the FP antenna after applying PRS, based on Example 2 of this invention. Figure 12 This demonstrates that the present invention achieves impedance matching in the range of 10.3 to 10.7 GHz.

[0052] Simulation 8 simulates the overall efficiency and peak gain achievable by the FP antenna after PRS loading, based on Example 2 of the present invention. Figure 13 As shown, the antenna maintains a radiation efficiency of 60% to 70% within the operating frequency band, and can achieve a peak gain of 15 dBi at 10.5 GHz.

[0053] Simulation 9 simulates the single-site RCS reduction performance of the FP antenna after applying PRS, based on Example 2 of this invention. Figure 14 As shown, due to the loading of the absorbing PRS, the overall structure achieves ultra-wideband RCS reduction in the range of 6 to 30 GHz, with a relative bandwidth of 133% and a peak reduction of 35 dB. Moreover, the RCS reduction in the operating frequency band is greater than 10 dB.

[0054] The simulation results above demonstrate that the low RCS FP resonant cavity antenna based on a lossy metasurface and AMC structure of this invention simultaneously achieves the three functions of low RCS, high gain, and low profile through the absorptive partial reflective surface structure and the bottom feed antenna structure, which simplifies the design of FP antennas and improves the shortcomings of existing technologies.

[0055] It is worth noting that the terms "first" and "second" in this invention are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0056] Although this application has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality.

[0057] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A low RCS FP resonant cavity antenna based on a lossy metasurface and an AMC structure, characterized in that: include: An absorbing partially reflecting surface structure (1) located at the upper portion and a feed antenna structure (2) located at the lower portion; The absorption-type partially reflective surface structure (1) comprises a lossy super surface layer (11), a metal patch common ground layer (12), a metal patch AMC1 layer (13), a first dielectric substrate layer (14) and a second dielectric substrate layer (15); the first dielectric substrate layer (14) is arranged between the lossy super surface layer (11) and the metal patch common ground layer (12), and the second dielectric substrate layer (15) is arranged between the metal patch common ground layer (12) and the metal patch AMC1 layer (13); The feed antenna structure (2) comprises an antenna patch layer (21), a metal floor layer (22), a coaxial structure (23) and a third dielectric substrate layer (24); the antenna patch layer (21) and the metal floor layer (22) are both arranged on the third dielectric substrate layer (24) and are arranged relative to each other; and the coaxial structure (23) is connected between the antenna patch layer (21) and the metal floor layer (22).

2. The low RCS FP resonant cavity antenna based on lossy metasurface and AMC structure according to claim 1, characterized in that: The lossy super surface layer (11), the metal patch common layer (12), and the metal patch AMC1 layer (13) are composed of a plurality of units with the same period, and the period size of each unit is in the range of 0.245λ t ≤p1≤0.256λ t ,λ t =c / f t , where λ t is the antenna operating center frequency f t The corresponding wavelength, c is the speed of light in vacuum, f t is the antenna operating center frequency.

3. The low RCS FP resonant cavity antenna based on lossy metasurface and AMC structure according to claim 2, characterized in that: Each unit of the lossy super surface layer (11) is composed of a square thin film resistor (111); each unit of the metal patch common ground layer (12) is composed of a first square metal patch (121); and each unit of the metal patch AMC1 layer (13) is composed of a second square metal patch (131).

4. The low RCS FP resonant cavity antenna based on lossy metasurface and AMC structure according to claim 3, characterized in that: The square thin film resistor (111) is a graphene resistor film, the square resistance thereof has a value range of 30 Ohm / sq to 100 Ohm / sq, and the side length a1 thereof has a value range of 0.147λ t ≤a1≤0.168λ t .

5. The low RCS FP resonant cavity antenna based on lossy metasurface and AMC structure according to claim 3, characterized in that: The side length a2 of the first square metal patch (121) has a value range of 0.241λ t ≤a2≤0.253λ t .

6. The low RCS FP resonant cavity antenna based on lossy metasurface and AMC structure according to claim 3, characterized in that: The side length a3 of the second square metal patch (131) is in the range of 0.140λ t ≤a3≤0.182λ t .

7. The low RCS FP resonant cavity antenna based on lossy metasurface and AMC structure according to claim 1, characterized in that: The antenna patch layer (21) is composed of a rectangular metal radiation patch (211) and a metal patch AMC2 structure (212) laid around the rectangular metal radiation patch (211); The length l of the metal radiation patch (211) has a value range of 0.280λ t ≤l≤0.297λ t , the value range of width w is 0.228λ t ≤w≤0.238λ t The metal patch AMC2 structure (212) is composed of periodically arranged third-party truncated metal patches, and the side length a4 of the third-party truncated metal patch is in the range of 0.161λ t ≤a4≤0.165λ t The value range of the spacing distance g between the third-party rectangular metal patches is 0.019λ t ≤g≤0.021λ t .

8. The low RCS FP resonant cavity antenna based on lossy metasurface and AMC structure according to claim 1, characterized in that: The side length p of the metal floor layer (22) has a value range of 2.450λ t ≤p≤2.842λ t .

9. The low RCS FP resonant cavity antenna based on lossy metasurface and AMC structure according to claim 7, characterized in that: The feeding center of the coaxial structure (23) is located at a position y1 offset from the geometric center of the metal radiation patch (211) along the y-axis, and the value range of the offset distance y1 is 0.046λ t ≤y1≤0.067λ t ; The coaxial structure (23) has an inner conductor radius r i =0.3mm, outer conductor radius r o =1.05mm coaxial probe structure.

10. The low RCS FP resonant cavity antenna based on lossy metasurface and AMC structure according to claim 1, characterized in that: The first dielectric substrate layer (14) is a dielectric with a thickness of h2=2.5 mm and a dielectric constant of 2.65; The second dielectric substrate layer (15) is a dielectric with a thickness of h3=2.5 mm and a dielectric constant of 2.65; The third dielectric substrate layer (24) is a dielectric with a thickness of h1=2.0 mm and a dielectric constant of 2.65.

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