A low-scattering resonant cavity antenna

Abstract

The application discloses a low-scattering resonant cavity antenna and belongs to the technical field of antenna radar scattering cross section reduction. The antenna comprises, from top to bottom, a scattering reduction layer, a foam layer and an antenna layer. The upper surface AMC layer of the scattering reduction layer is divided into eight triangular regions by the center of a square substrate. Four non-adjacent triangular regions are arranged with first AMC units. The remaining triangular regions are divided into inner and outer regions and arranged with second and third AMC units. X and Ku full-band wideband RCS reduction is realized by relying on phase difference interference. The lower surface of the scattering reduction layer is a partially reflective surface layer with 12*12 orthogonal slits. The foam layer and the upper and lower structures form a Fabry-Perot resonant cavity to improve the normal gain. The antenna layer is provided with a microstrip patch array and a power division feed network, and the bottom metal floor suppresses back radiation. The application realizes more than 6dB RCS reduction in the X and Ku bands, the overall profile is only 0.18lambda, the maximum gain reaches 17.22dBi, and the application has the advantages of wide frequency, low scattering, high gain and small size.

Description

Technical Field

[0001] This invention belongs to the field of antenna radar cross section reduction technology, specifically relating to a low-scattering resonant cavity antenna that achieves RCS reduction of more than 6dB across the entire X-band and Ku-band frequency bands. Background Technology

[0002] In today's information- and electronic warfare, seizing electromagnetic dominance has become a key factor in determining victory or defeat. With the rapid development of radar detection, precision guidance, and electronic warfare technologies, the battlefield survivability of weaponry faces unprecedented challenges. Stealth technology, as a core technology for improving the penetration capability and survivability of weaponry, has become a commanding height in the military technology competition among nations. For airborne platforms such as combat aircraft and cruise missiles, reducing their radar cross section (RCS) is the primary means of achieving low observability; "undetectable and therefore unhittable" has become the golden rule of designing next-generation main battle equipment.

[0003] In stealth design for aircraft, the fuselage shape can significantly reduce the radar cross-section (RCS) through special geometric designs (such as the parallel principle and blended wing-body) and the application of radar-absorbing materials. However, the antenna system, as the "eyes" and "ears" of the aircraft, undertakes indispensable tasks such as communication, navigation, detection, and guidance. Because antennas must be exposed on the fuselage surface or housed in a radar-transparent radome to effectively transmit and receive electromagnetic waves, and are typically made of good conductors, they often become strong scattering sources on stealth platforms. Related research shows that at certain detection angles and frequencies, the RCS contribution of the antenna system may even exceed the total RCS contribution of the fuselage itself. This inherent contradiction between "strong radiation" and "low scattering" makes antenna RCS reduction a pressing problem in the field of stealth technology.

[0004] Microstrip patch antenna arrays are widely used in X-band airborne fire control radar and satellite communication systems due to their advantages such as low profile, light weight, easy conformal integration with the carrier, and ease of integration. However, the X-band is not only the operating frequency band of friendly antennas but also the main detection frequency band of enemy fire control radars; meanwhile, the higher-frequency Ku-band is often used in missile terminal guidance radar and high-resolution imaging radar. Therefore, in order to cope with the complex and ever-changing electromagnetic threats on the battlefield, antenna systems not only need to achieve "in-band stealth" within the operating frequency band (X-band) but also "out-of-band stealth" at higher frequencies (Ku-band), that is, to achieve ultra-wideband RCS reduction covering the X+Ku band.

[0005] Traditional RCS reduction methods, such as shape modification techniques, while effective for structural scattering, often disrupt the antenna's radiation pattern, leading to decreased gain or increased sidelobes. While loading traditional absorbing materials can absorb incident wave energy, they often suffer from narrow bandwidth, heavy weight, and the tendency to absorb the antenna's own radiated energy, thus reducing radiation efficiency. Therefore, exploring a new technology that can achieve wideband RCS reduction while maximizing antenna radiation performance has significant academic value and promising military applications.

[0006] In recent years, the development of artificial magnetic conductor technology has provided new ideas for solving this problem. Artificial magnetic conductors (AMCs), as artificial electromagnetic structures with high impedance surface characteristics, can achieve in-phase reflection of incident electromagnetic waves (reflection phase is 0) within a specific frequency range. This is different from the anti-phase reflection of a traditional metallic ground plane (reflection phase is 180°). This is completely different. By utilizing this characteristic, AMC elements can be arranged in a checkerboard pattern with metal surfaces (PEC) or AMC elements with different reflection phases. The principle of wave interference and destructive force can be used to scatter the radar echo energy that was originally concentrated in the direction of mirror reflection into the non-threat airspace, thereby significantly reducing the single-station RCS.

[0007] However, existing artificial magnetic conductor (AMC) technology still faces many challenges in practical applications. First, the in-phase reflection bandwidth of conventional AMC structures is relatively narrow, making it difficult to simultaneously cover the X-band and Ku-band, thus failing to meet the requirements for broadband stealth across frequency bands. Second, when an AMC structure is loaded around an antenna array, its unique electromagnetic boundary conditions easily lead to strong coupling with the antenna's near-field, resulting in problems such as antenna impedance mismatch, center frequency shift, beam distortion, and an increase in the absolute value of the RCS. Especially for antennas operating in the X-band, how to achieve broadband RCS reduction in the X+Ku band while ensuring that the in-band radiation performance of the X-band remains unaffected is a complex multiphysics problem involving electromagnetic fields and microwave technology, materials science, and array antenna theory. Summary of the Invention

[0008] To address the limitations of existing RCS reduction techniques based on AMC structures, such as limited bandwidth reduction, impact on array antenna gain, and increased overall size and absolute RCS due to large array configurations, this invention provides a low-scattering resonant cavity array antenna. This invention introduces a windmill-shaped AMC structure into the Fabry-Perot resonant cavity antenna and employs a partitioned loading method within the AMC structure. Without reducing the array antenna gain, it achieves wideband RCS reduction across the entire X and Ku bands at a relatively low profile height, while also exhibiting high gain, low scattering, and miniaturization characteristics.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A low-scattering resonant cavity array antenna is characterized by comprising a scattering reduction layer, a foam layer, and an antenna layer arranged sequentially from top to bottom.

[0011] The scattering reduction layer includes a first dielectric substrate, an AMC layer disposed on its upper surface, and a partial reflective surface layer disposed on its lower surface. The first dielectric substrate is a square dielectric substrate. The AMC layer is divided into eight equally sized triangular regions by orthogonal midlines and two diagonals, with the center point of the square dielectric substrate as a reference. The eight triangular regions are divided into two groups, in which the first AMC unit is evenly arranged in four non-adjacent triangular regions. The remaining four triangular regions are divided into inner and outer regions, with the third AMC unit evenly arranged in the inner region and the second AMC unit evenly arranged in the outer region. By arranging the three types of AMC units in a staggered manner, a reflection phase difference of approximately 180° is formed between the X-band and Ku-band, and the reduction of the wideband radar cross section (RCS) is achieved through electromagnetic wave destructive interference. The partial reflective surface layer is composed of 12×12 mutually orthogonal slots on a metal layer, with the intersection of 16 slots facing the center of each radiator patch unit in the antenna array.

[0012] The foam layer is used to support and isolate the scatter reduction layer and the antenna radiation layer, and together with the partial reflective surface layer and the metal ground layer, it forms a Fabry-Perot resonant cavity. Electromagnetic waves in the resonant cavity are reflected and superimposed in phase multiple times to improve the antenna normal radiation gain.

[0013] The antenna layer includes a second dielectric substrate, a microstrip patch array and a power divider feed network disposed on its upper surface, and a metal ground plane disposed on its lower surface; the microstrip patch array includes radiator patch units arranged in a 4×4 periodic pattern; the power divider feed network is a 1 to 16 microstrip power divider used to feed each radiator patch unit; the metal ground plane is used to suppress antenna back radiation.

[0014] Preferably, the period of the first AMC unit is a square period, which is divided into four square sub-regions. Large square metal patches are provided in the two diagonally opposite square sub-regions, and small square metal patches are provided in the other two square sub-regions. Each square metal patch is located at the center of its corresponding sub-region.

[0015] Preferably, the period of the second AMC unit is the same as that of the first AMC unit; the second AMC unit is a 90-degree rotationally symmetrical structure composed of a cross-shaped metal patch and a multi-level square metal patch; the multi-level square metal patch is composed of one primary square metal patch, four secondary square metal patches, and twelve tertiary square metal patches; wherein, the center of the cross-shaped metal patch coincides with the geometric center of the primary square metal patch, the four secondary square metal patches are respectively located at the four outer corners of the primary square metal patch, and a tertiary square metal patch is arranged at each of the three outer corners of each secondary square metal patch.

[0016] Preferably, the third AMC unit has the same period as the second AMC unit, the same topology as the second AMC unit, but different dimensions.

[0017] Preferably, the width of the gap is 1.00 mm.

[0018] Preferably, the spacing of the gaps is 7.50 mm.

[0019] Preferably, the radiator patch unit is a square metal patch structure.

[0020] Preferably, the 1-to-16 microstrip power divider is composed of multiple T-type power dividers.

[0021] This invention's scattering reduction layer is based on a windmill-like arrangement, dividing a square substrate into eight equally spaced triangular windmill blade regions. Four non-adjacent triangular regions are fully arranged with the first AMC (Air-Mounted Multi-Chip) unit, while the remaining four triangular blades are further divided into inner and outer sub-regions. The inner region houses the third AMC unit, and the outer region houses the second AMC unit. Through this composite arrangement of three types of AMC units in a windmill-like layout with local subdivision, the interference cancellation principle of waves between different AMC structures is utilized to scatter the radar echo energy originally concentrated in the specular reflection direction into a non-threatening airspace, thereby significantly reducing the single-station RCS. A foam layer fills the space between the scattering reduction layer and the antenna radiating layer, serving both as a dielectric support and equivalent to an air medium. Together with the upper reflective surface and the lower metal ground plane, it constructs the Fabry-Perot resonant cavity. The antenna layer uses a 1-to-16 power divider to divide the 4... The four-antenna array is fed with equal amplitude and in phase, which allows the antenna array to radiate energy in the form of electromagnetic waves. The electromagnetic waves are reflected multiple times in the cavity to form in-phase superposition, which improves the normal radiation gain. The bottom of the antenna is covered with a metal ground plane to completely reflect the downward propagating electromagnetic waves and effectively suppress the antenna's back radiation.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention achieves a broadband RCS reduction of more than 6dB in the 6.71~18.36GHz frequency band without affecting the radiation performance of the array antenna by using a windmill-shaped arrangement and a partitioned loading AMC structure. The reduced frequency band completely covers the entire X-band and Ku-band, thus meeting the requirements of low scattering design for the array antenna in the X-band and Ku-band.

[0024] 2. This invention introduces an integrated design scheme that incorporates a Fabry-Perot resonant cavity antenna and arranges an AMC structure on top of it. This design reduces the overall array profile height to only 0.18λ of the operating frequency wavelength. Compared to the common integrated design scheme that arranges the AMC structure in a checkerboard pattern around the antenna array, the overall size is reduced by nearly 40%, meeting the requirements for device miniaturization.

[0025] 3. The antenna array composed of antenna elements of the present invention introduces a Fabry-Perot resonant cavity antenna, which forms in-phase superposition through multiple reflections within the cavity, thereby improving the normal radiation gain. Furthermore, by utilizing the coupling effect between the AMC structure and the antenna array in the vertical direction, the in-band gain is significantly improved, with a maximum gain of 17.22 dBi, thus meeting the high gain requirements of the array antenna. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. It should be noted that the drawings described below are merely embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of the low-scattering resonant cavity antenna provided in an embodiment of the present invention.

[0028] Figure 2 The diagram shows three windmill-style layouts of AMC units provided in the embodiments of the present invention.

[0029] Figure 3 These are schematic diagrams of two existing AMC unit windmill-style arrangements.

[0030] Figure 4 This is a schematic diagram of a first type of AMC unit provided in an embodiment of the present invention.

[0031] Figure 5 This is a top view of a first type of AMC unit provided in an embodiment of the present invention.

[0032] Figure 6 This is a schematic diagram of a second type of AMC unit provided in an embodiment of the present invention.

[0033] Figure 7 This is a top view of a second AMC unit provided in an embodiment of the present invention.

[0034] Figure 8 This is a schematic diagram of a third type of AMC unit provided in an embodiment of the present invention.

[0035] Figure 9 This is a top view of a third AMC unit provided in an embodiment of the present invention.

[0036] Figure 10 This is a schematic diagram of the PRS on the lower surface of the scattering reduction layer provided in an embodiment of the present invention.

[0037] Figure 11 This is a schematic diagram of the foam layer structure provided in an embodiment of the present invention.

[0038] Figure 12 This is a schematic diagram of the antenna radiating layer provided in an embodiment of the present invention.

[0039] Figure 13 This is a top view of the antenna radiating layer provided in an embodiment of the present invention.

[0040] Figure 14 This is a schematic diagram of the final stage structure of the 1-to-16 power divider of the antenna unit in an embodiment of the present invention.

[0041] Figure 15 This is a schematic diagram of the metal ground plane of the array antenna in an embodiment of the present invention.

[0042] Figure 16 The following are simulation diagrams of the reflection phase curves of three AMC units in the embodiments of the present invention.

[0043] Figure 17 The figure shows the simulation results of the single-site RCS comparison of the antenna in the embodiment of the present invention.

[0044] Figure 18 This is a comparison of the radiation gain pattern of the antenna E-plane in an embodiment of the present invention.

[0045] Figure 19 This is a comparison of the radiation gain pattern of the antenna H-plane in an embodiment of the present invention.

[0046] Explanation of reference numerals in the attached figures:

[0047] 1-AMC layer, 10-First AMC unit, 11-Second AMC unit, 12-Third AMC unit, 100-Large square metal patch, 101-Small square metal patch; 2-First dielectric substrate; 3-Partial reflective surface layer, 30-Gap; 4-Foam layer; 5-Antenna radiating layer, 51-Radiator patch unit, 52-Power divider feed network, 520-Power divider wiring corner chamfer, 521-Power divider branch corner chamfer; 6-Second dielectric substrate; 7-Metal ground plane layer. Detailed Implementation

[0048] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0049] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0051] This embodiment provides a low-scattering resonant cavity antenna, such as Figure 1 As shown, the antenna includes, from top to bottom, a scattering reduction layer, a foam layer, and an antenna layer. The overall antenna dimensions (length) are as follows. Width Height is 171.5mm 171.5mm 5.38mm, corresponding to 5.72K of the operating frequency wavelength. 5.72k 0.18k

[0052] The scattering reduction layer includes a first dielectric substrate, an AMC layer disposed on its upper surface, and a partially reflective surface layer disposed on its lower surface.

[0053] The first dielectric substrate is a square dielectric substrate with a length and width of 171.5 mm. Rogers RT / duroid 5880, with a thickness of 171.5 mm and a thickness of 2.032 mm, has a relative permittivity of 2.2.

[0054] like Figure 2 As shown, the AMC layer, with the center point of the square dielectric substrate as the reference, is divided into eight equally sized triangular regions by orthogonal centerlines and two diagonals. The eight triangular regions are divided into two groups, in which the first AMC unit is evenly arranged in four non-adjacent triangular regions; the remaining four triangular regions are divided into inner and outer regions, with the third AMC unit evenly arranged in the inner region and the second AMC unit evenly arranged in the outer region. The three types of AMC units are periodically continuous at the boundaries of adjacent partitions, without any blank or discontinuous areas. By arranging the three types of AMC units in a staggered manner, a reflection phase difference of approximately 180° is formed between the X-band and Ku-band, and the broadband radar cross section (RCS) is reduced through electromagnetic wave destructive interference.

[0055] like Figure 4-5 As shown, the period of the first AMC unit is a square period with a side length of 8.5mm. The square period is divided into four square sub-regions. Large square metal patches with a side length of 3mm are set in the two diagonally opposite square sub-regions, and small square metal patches with a side length of 2.5mm are set in the other two square sub-regions. Each square metal patch is set at the center of its corresponding sub-region.

[0056] like Figure 6-7 As shown, the period of the second AMC unit is the same as that of the first AMC unit; the second AMC unit is a 90-degree rotationally symmetrical structure composed of a cross-shaped metal patch and multiple layers of square metal patches; the length and width of the two rectangular arms of the cross-shaped metal patch are 7mm respectively. 1.4mm; The multi-level square metal patch consists of one primary square metal patch with a side length of 5.1mm, four secondary square metal patches with a side length of 1.8mm, and twelve tertiary square metal patches with a side length of 0.8mm; wherein, the center of the cross-shaped metal patch coincides with the geometric center of the primary square metal patch, the four secondary square metal patches are respectively located at the four outer corners of the primary square metal patch, and a tertiary square metal patch is arranged at each of the three outer corners of each secondary square metal patch.

[0057] like Figure 8-9 As shown, the third AMC unit has the same period as the second AMC unit, but different structural parameters; the length and width of the two rectangular arms of its cross-shaped metal patch are 6mm respectively. The side length of the first-level square metal patch is 5.1mm, the side length of the second-level square metal patch is 1.3mm, and the side length of the third-level square metal patch is 0.6mm.

[0058] like Figure 10 As shown, the partially reflective surface layer consists of a 161.5mm wide area covering the center of the lower surface of the substrate. The metal layer in the 161.5mm region is formed by 12×12 mutually orthogonal slots, each slot being 1.00mm wide and spaced 7.5mm apart, with 16 of the slots intersecting at the center of each radiator patch element in the antenna array.

[0059] like Figure 11 As shown, the foam layer has a dielectric constant of 1.05 and dimensions of 171.5 mm (length and width). A 171.5mm thick foam with a thickness of 2.84mm is used to support and isolate the scatter reduction layer from the antenna radiation layer. Together with a partial reflective surface layer and a metal ground layer, it forms a Fabry-Perot resonant cavity. Electromagnetic waves in the resonant cavity undergo multiple reflections and in-phase superposition to enhance the antenna's normal radiation gain.

[0060] like Figure 12 As shown, the antenna layer includes a second dielectric substrate, a microstrip patch array and a power divider feed network disposed on its upper surface, and a metal ground plane disposed on its lower surface.

[0061] The second dielectric substrate is made of a material with dimensions of 171.5 mm in length and width. Rogers RT / duroid 5880, 171.5mm thick and 0.508mm wide.

[0062] like Figure 13-14 As shown, the microstrip patch array includes 4×4 periodically arranged square radiator patch units, each of which is a square metal patch with a side length of 10mm, and the spacing between the antenna units is 15.5mm. The power divider feed network is a 1-to-16 microstrip power divider composed of multiple T-type power dividers, used to feed each radiator patch unit; wherein, the input feed line of the power divider feed network is a 50Ω impedance microstrip line with an input linewidth of 1.5mm, and the structure diagram of its last stage 1-to-4 feed terminal is shown in the figure. Figure 14 As shown, considering the need to maintain phase consistency when feeding the antenna array, the feeding direction of each feeding branch of the final 1-to-4 power divider must be kept consistent. Simultaneously, to reduce feeding loss, all corners during wiring are cut at a 45-degree angle with an input line width of 1.5mm. When branching, a triangle with a base of 1.5mm and a height of 0.6mm is cut at the center of the branch, with a branch line width of 1mm and a branch length of 3mm. The aforementioned 1-to-4 power divider is then connected to a T-type 1-to-2 power divider to form a 1-to-16 power divider. Each final output branch has the same feeding direction, corresponding to feeding one antenna element. The metal ground plane, as... Figure 15As shown, a square floor is used to suppress back radiation from the antenna.

[0063] See Figure 16 The figures show the simulation results of the reflection phase curves of the three AMC units in this example; the black curve represents the reflection phase curve of the first AMC unit, the red curve represents the reflection phase curve of the second AMC unit, and the blue curve represents the reflection phase curve of the third AMC unit. It can be seen that the original reflection phase difference between the first and second AMC units was 10~12 GHz, which is 180° away from the 180° reflection phase difference. The two AMC units are not close enough, resulting in poor destructive interference in the 10-12 GHz range, which in turn leads to poor RCS reduction in the same range. Adding a third AMC unit brings the reflection phase difference between it and the first AMC unit in the 10-12 GHz range closer to 180°. However, the reflection phase difference in the 8-10 GHz range is too low, so the second AMC unit cannot be completely replaced by the third AMC unit. Instead, the method of loading the three AMC units in sections is used to make the destructive interference effect of the three AMC units in the 8-18 GHz range meet the requirements.

[0064] See Figure 17 The figures show the single-site RCS simulation results for this example. The black curve represents the reference single-site RCS curve without AMC units, the blue curve represents the single-site RCS curve without partition loading, using only the first and second types of AMC units arranged in a windmill pattern, and the red curve represents the single-site RCS curve with partition loading of all three types of AMC units in this example. It can be seen that without partition loading, the RCS reduction frequency bands above 6dB are only 9.98~10.56GHz and 12.04~1GHz. At 8.38 GHz, the coverage of the X and Ku bands was not complete. However, after partitioning and loading three types of AMC units, the RCS reduction band of more than 6 dB was 6.71~18.36 GHz, with two reduction peaks. At 10.7 GHz, the RCS value was reduced from 12.14 dBsm to -7.67 dBsm, a reduction of 19.81 dB, and at 15.1 GHz, the RCS value was reduced from 14.32 dBsm to -6.32 dBsm, a reduction of 20.64 dB. In summary, partitioning and loading three types of AMC units significantly improved the RCS reduction effect in the 8-12 GHz range compared to the unpartitioned approach. The improved 6 dB reduction band completely covered the entire X and Ku bands, and the reduction at the reduction peaks was also greatly increased, meeting the design requirements.

[0065] See Figure 18 and Figure 19 The above represents the simulation results of the radiation performance of the antenna element in this example; where... Figure 18 and Figure 19The image shows the gain graphs of the antenna in the E-plane and H-plane at the resonant frequency of 9.45 GHz. The black curve represents the antenna array gain without AMC elements, and the red curve represents the antenna array gain after partitioning with three types of AMC elements. It can be seen that the antenna array without AMC elements has a maximum gain of approximately 13.95 dBi, a main lobe width of 38°, a half-beamwidth of approximately 23.13°, and a maximum sidelobe gain of approximately 9.76 dBi. In contrast, the antenna array with partitioned AMC elements has a maximum gain of approximately 17.22 dBi, a main lobe width of 48°, a half-beamwidth of 31.7°, and a maximum sidelobe gain of approximately 9.16 dBi. This demonstrates that partitioning with windmill-shaped AMC elements not only did not reduce the antenna array gain but actually increased its main lobe gain and reduced the maximum sidelobe gain, achieving the overall design requirements of high gain, low scattering, and miniaturization.

Claims

1. A low-scattering resonant cavity array antenna, comprising a scattering reduction layer, a foam layer, and an antenna layer arranged sequentially from top to bottom; Its features are, The scattering reduction layer includes a first dielectric substrate, an AMC layer disposed on its upper surface, and a partial reflective surface layer disposed on its lower surface. The first dielectric substrate is a square dielectric substrate. The AMC layer is divided into eight equally sized triangular regions by orthogonal midlines and two diagonals, with the center point of the square dielectric substrate as a reference. The eight triangular regions are divided into two groups, in which the first AMC unit is evenly arranged in four non-adjacent triangular regions. The remaining four triangular regions are divided into inner and outer regions, with the third AMC unit evenly arranged in the inner region and the second AMC unit evenly arranged in the outer region. By arranging the three types of AMC units in a staggered manner, a reflection phase difference of approximately 180° is formed between the X-band and Ku-band, and the reduction of the wideband radar cross section (RCS) is achieved through electromagnetic wave destructive interference. The partial reflective surface layer is composed of 12×12 mutually orthogonal slots on a metal layer, with the intersection of 16 slots facing the center of each radiator patch unit in the antenna array. The foam layer is used to support and isolate the scatter reduction layer and the antenna radiation layer, and together with the partial reflective surface layer and the metal ground layer, it forms a Fabry-Perot resonant cavity. The electromagnetic waves in the resonant cavity are reflected and superimposed in phase multiple times to improve the antenna normal radiation gain. The antenna layer includes a second dielectric substrate, a microstrip patch array and a power divider feed network disposed on its upper surface, and a metal ground plane disposed on its lower surface; the microstrip patch array includes radiator patch units arranged in a 4×4 periodic pattern; the power divider feed network is a 1 to 16 microstrip power divider used to feed each radiator patch unit. The metal floor layer is used to suppress back radiation from the antenna.

2. The low-scattering resonant cavity array antenna as described in claim 1, characterized in that, The first AMC unit has a square period, which is divided into four square sub-regions. Large square metal patches are set in the two diagonally opposite square sub-regions, and small square metal patches are set in the other two square sub-regions. Each square metal patch is located at the center of its corresponding sub-region.

3. A low-scattering resonant cavity array antenna as described in claim 2, characterized in that... The period of the second AMC unit is the same as that of the first AMC unit; the second AMC unit is a 90-degree rotationally symmetrical structure composed of a cross-shaped metal patch and a multi-level square metal patch; the multi-level square metal patch is composed of one primary square metal patch, four secondary square metal patches, and twelve tertiary square metal patches; wherein, the center of the cross-shaped metal patch coincides with the geometric center of the primary square metal patch, the four secondary square metal patches are respectively located at the four outer corners of the primary square metal patch, and a tertiary square metal patch is arranged at each of the three outer corners of each secondary square metal patch.

4. A low-scattering resonant cavity array antenna as described in claim 3, characterized in that... The third AMC unit has the same period as the second AMC unit, the same topology as the second AMC unit, but different dimensions.

5. A low-scattering resonant cavity array antenna as described in claim 4, characterized in that... The width of the gap is 1.00 mm.

6. A low-scattering resonant cavity array antenna as described in claim 5, characterized in that... The spacing of the gaps is 7.50 mm.

7. A low-scattering resonant cavity array antenna as described in any one of claims 4-6, characterized in that... The radiator patch unit is a square metal patch structure.

8. A low-scattering resonant cavity array antenna as described in claim 7, characterized in that... The 1 to 16 microstrip power divider is composed of multiple T-type power dividers.

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