A compact low RCS metasurface antenna array and its design method

Abstract

The present invention discloses a compact low RCS metasurface antenna array and a design method thereof, wherein the antenna array comprises: a metal patch layer, an intermediate dielectric layer, a metal backplane layer, and a plurality of coaxial metal feed posts, wherein the metal patch layer, the intermediate dielectric layer, and the metal backplane layer are seamlessly stacked in sequence from top to bottom; and the plurality of coaxial metal feed posts respectively penetrate the metal patch layer, the intermediate dielectric layer, and the metal backplane layer. The present invention realizes the coherent cancellation of the scattered field of the entire antenna by arranging two types of radiation units in a chessboard array, and disperses them to non-threatening angles, thereby realizing the characteristics of the antenna with a wide-band low radar cross-section.

Description

Technical Field

[0001] The present invention belongs to the field of antenna technology, and specifically refers to a compact low RCS metasurface antenna array and a design method thereof. Background Art

[0002] In today's high-tech electronic warfare, stealth technology is an important component, which has a significant impact on the survival and combat capabilities of various weapons and equipment. Antennas are an important part of various combat platforms, and they are structures with strong scattering characteristics in the target system. Therefore, effectively controlling and reducing the radar cross section (RCS) of the antenna has become the key to designing a low-detectability radar system.

[0003] A metasurface is a metal array with a subwavelength structure that can flexibly manipulate electromagnetic waves, thereby achieving artificial control of the amplitude, phase, and polarization characteristics of reflected or transmitted waves. In recent years, metasurfaces have been widely studied for their flexible design in low RCS antennas. Although many literatures have achieved RCS reduction of antenna arrays by loading metasurfaces, the metasurface units and antenna arrays are designed independently during design, and the overall size of the antenna needs to be increased. Therefore, it is particularly important to find an effective way to reduce the in-band and out-of-band RCS of the antenna while ensuring that its radiation characteristics are not affected.

[0004] According to the radar equation, the detection range of the enemy radar is proportional to the fourth square root of the target's RCS. Therefore, for every 10 dB reduction in RCS, the corresponding detection range is reduced to 56%, and the radar range is reduced by 44%. Therefore, reducing the antenna's RCS is the key to enhancing the survivability of various combat platforms.

[0005] Journal article: M. Guo, B. Xue, J. Wang and G. Yang, "Circularly polarised antenna with low RCS using chessboard grid hollow substrate," in Electronics Letters, vol. 55, no. 24, pp. 1265-1267, 28 11 2019. The article proposes a low RCS circular antenna array based on a chessboard structured empty substrate. The simulation results show that the RCS of the antenna in the 7-21GHz range of the low RCS circular antenna array is reduced, but the relative bandwidth of the RCS reduction value of the antenna is greater than 10dB is 30%, and the average RCS reduction value in the antenna working frequency band is only 5dB. As a low RCS antenna array, in addition to having good scattering characteristics, the radiation characteristics cannot be affected too much. Due to the loading of the empty substrate, the antenna array has only 50% effective radiation units. Compared with the reference antenna array, the radiation characteristics are greatly affected and obviously need to be improved.

[0006] Journal article: Y. Fan, J. Wang, Y. Li, J. Zhang, Y. Han and S. Qu, "Low-RCS and High-Gain Circularly Polarized Metasurface Antenna," in IEEE Transactions on Antennas and Propagation, vol. 67, no. 12, pp. 7197-7203, Dec. 2019. The article proposes a low RCS antenna array arranged in a chessboard structure by rotating the radiating units. The simulation results show that the RCS of the antenna in the 8-14 GHz range of the low RCS antenna array is reduced. The antenna array makes full use of the area of ​​the radiating unit and integrates the antenna and the metasurface. Compared with the reference antenna array, the radiation characteristics are not greatly affected, but the relative bandwidth of the RCS reduction value of the antenna greater than 10 dB is only 8%, and the average RCS reduction value in the antenna working frequency band is only 4 dB, which fails to achieve a good reduction in the radar scattering cross section within the antenna working frequency band. Summary of the invention

[0007] In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a compact low RCS metasurface antenna array and a design method thereof, so as to solve the problems in the prior art that the RCS reduction value of the antenna is greater than 10 dB, the relative bandwidth is narrow, and the proportion of effective radiation units of the low RCS antenna array is not high. The present invention ensures the radiation characteristics of the antenna array while greatly reducing the radar cross section within the antenna operating frequency band, and ensures that the RCS reduction value of the designed antenna array is greater than 10 dB, and the relative bandwidth is greater than that of the antenna array designed by the prior art, and the low profile and easy processing characteristics of the present invention facilitate integration with circuits.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A compact low RCS metasurface antenna array of the present invention comprises: a metal patch layer, an intermediate dielectric layer, a metal backplane layer and a plurality of coaxial metal feed poles, wherein the metal patch layer, the intermediate dielectric layer and the metal backplane layer are seamlessly stacked in sequence from top to bottom; and the plurality of coaxial metal feed poles respectively penetrate the metal patch layer, the intermediate dielectric layer and the metal backplane layer.

[0010] Furthermore, the metal patch layer includes a first rectangular patch unit and a second bidirectional comb-tooth patch unit, the first rectangular patch unit is a rectangular patch with a regular shape, and the second bidirectional comb-tooth patch unit is a bidirectional comb-tooth patch with eight comb-tooth structures loaded on both sides of the radiation edge after the size of the first rectangular patch unit is adjusted.

[0011] Furthermore, the reflection phase difference between the first rectangular patch unit and the second bidirectional comb-shaped patch unit satisfies 180°±37°, and they are printed and arranged in a 4*4 period on the intermediate dielectric layer in a checkerboard structure.

[0012] Furthermore, the intermediate dielectric layer is made of a material of 80mm*80mm*3mm, which is an F4B substrate with a dielectric constant of 2.65 and a loss tangent of 0.001.

[0013] Furthermore, assuming that the antenna array includes 4*4 patch units, it has 4*4 feeding points accordingly, and the 4*4 feeding points are regularly arranged below the 4*4 patch units.

[0014] Furthermore, the metal backplane layer has a conductivity of σ=5.8×10 7 S / m copper material, size is 80mm*80mm.

[0015] A design method of a compact low RCS metasurface antenna array of the present invention comprises the following steps:

[0016] 1) Derived the size of the first rectangular patch unit according to the resonant frequency calculation formula of the antenna array, and determined the position of the metal feeding column of the first rectangular patch unit;

[0017] 2) According to the reflection phase of the first rectangular patch unit, the size of the second bidirectional comb-shaped patch unit is determined by adjusting its size, and the reflection phases of the two obtained satisfy a phase difference of 180°±37°;

[0018] 3) According to the size of the second bidirectional comb-shaped patch unit and the calculation formula of the resonant frequency of the antenna array, the theoretical radiation side electrical length of the second bidirectional comb-shaped patch unit and the position of the metal feeding post of the second bidirectional comb-shaped patch unit are derived;

[0019] 4) According to the theoretical radiation side electrical length and size of the second bidirectional comb-tooth patch unit, a comb-tooth structure is added to the radiation side of the second bidirectional comb-tooth patch unit so that the radiation side length reaches the theoretical radiation side electrical length, and the size and position of the comb-tooth structure of the second bidirectional comb-tooth patch unit are adjusted and determined;

[0020] 5) Select a processing material, use copper clad plate technology to periodically print a metal patch layer consisting of the above two patch units on the upper surface of the processing material, and print a metal backplane layer on the lower surface of the processing material to obtain the designed compact low RCS metasurface antenna array.

[0021] Furthermore, the calculation formula for the size of the first rectangular patch unit in step 1) is: The calculation formula for the position of the metal feeding column of the first rectangular patch unit is: Where W1 is the width of the radiation side of the first rectangular patch unit, L1 is the length of the radiation side of the first rectangular patch unit, c0 is the propagation speed of light in vacuum, f0 is the specified resonant center frequency, ε r is the relative dielectric constant of the intermediate dielectric layer, c1 is the distance between the metal feeding column of the first rectangular patch unit and the center of the first rectangular patch unit, and h is the thickness of the intermediate dielectric layer.

[0022] Furthermore, the specific steps for adjusting the size of the first rectangular patch unit in the step 2) are as follows: without changing the width of the first rectangular patch unit, increase / decrease the length of the first rectangular patch unit, and when the length of the second bidirectional comb-tooth patch unit is L2, the reflection amplitude within the wide band is reduced when the x-polarized wave is incident, and at the same time, the reflection phase when the y-polarized wave is incident is not affected; without changing the length of the second bidirectional comb-tooth patch unit, increase / decrease the width of the second bidirectional comb-tooth patch unit, and when the length of the second bidirectional comb-tooth patch unit is W2, a phase difference of 180°±37° with the first rectangular patch unit is formed within the wide band when the y-polarized wave is incident, and at the same time, the reflection amplitude of the incident x-polarized wave is not affected.

[0023] Furthermore, the formula for the theoretical radiation side electrical length of the second bidirectional comb-shaped patch unit derived in step 3) is: The calculation formula for the position of the metal feeding post of the second bidirectional comb-shaped patch unit is: Wherein, L2 is the actual length of the radiation side of the second bidirectional comb-tooth patch unit, L2′ is the theoretical radiation side electrical length of the second bidirectional comb-tooth patch unit, c0 is the propagation speed of light in vacuum, f0 is the specified resonant center frequency, ε r is the relative dielectric constant of the intermediate dielectric layer, c2 is the distance between the metal feeding column of the second bidirectional comb-tooth patch unit and the center of the second bidirectional comb-tooth patch unit, and h is the thickness of the intermediate dielectric layer.

[0024] Furthermore, the specific steps of step 4) adjusting the comb tooth structure size of the second bidirectional comb tooth patch unit are as follows: without changing the actual length L2 and width W2 of the second bidirectional comb tooth patch unit, four comb tooth structures are loaded at the radiation edge of the second bidirectional comb tooth patch unit respectively to increase / decrease the length and width of the comb tooth structure. When the length of the comb tooth structure is d and the width is b, L2′≈L2+4d is achieved. At this time, the operating frequency band of the second bidirectional comb tooth patch unit as an antenna radiation unit is consistent with the operating frequency band of the first rectangular patch unit as an antenna radiation unit. At the same time, it does not affect the reflection amplitude of the second bidirectional comb tooth patch unit when the x-polarized wave is incident and the reflection phase when the y-polarized wave is incident.

[0025] Beneficial effects of the present invention:

[0026] The antenna array of the present invention has good radiation characteristics. Taking the 4*4 unit chessboard array as an example, the overall structure size is 8cm*8cm. It can be seen that its minimum working size will not cause difficulties in designing a low-detectability radar system. Among the 16 units, 8 first rectangular patch units and 8 second bidirectional comb-shaped patch units are included. Compared with the entire antenna consisting of only one type of patch unit, the characteristic of the chessboard array to achieve radar scattering cross-section reduction is reflected. The equivalent size of the first rectangular patch unit is 0.26λ0*0.28λ0, and the equivalent size of the second bidirectional comb-shaped patch unit is 0.22λ0*0.20λ0, where λ0 is the wavelength at the resonance point when the two metal patch units work as the radiating units of the antenna; S 11 The standard is ≤-10dB, the antenna array operating frequency band is 6.22-6.83GHz, and the gain is 16.01dB.

[0027] The antenna array of the present invention has good scattering characteristics. Compared with the reference antenna, the single-station RCS curve with frequency shows that the radar cross section can be reduced in the wide frequency band of 5.22-7.10GHz, and the radar cross section reduction is greater than 10dB in the 5.22-7.10GHz frequency band; the single-station RCS curve with incident angle at 6.4GHz shows that the radar cross section can be reduced in the angle range of -31 to 31°, and the radar cross section reduction is greater than 10dB in the angle range of -31 to 31°; the three-dimensional scattering pattern at 6.4GHz shows that under normal incidence, it is significantly reduced along the main plane (XZ, YZ), and the main reflection lobe points to four quadrants. At 6.4GHz, the RCS on the main plane of the metasurface antenna of the present invention is reduced by 10.2dB compared with the reference antenna. On the diagonal plane, the maximum RCS is 8.3dB smaller than the reference antenna. This reduction is because the reflected field is redirected to four main lobes instead of a single main lobe on the reference antenna surface; this shows that the metasurface antenna based on the chessboard structure of the present invention can significantly reduce the radar scattering cross section of the antenna, thereby achieving the stealth of the antenna.

[0028] The present invention ensures that the metasurface antenna does not affect the radiation characteristics while greatly reducing the single-station RCS covering the antenna working frequency band, wherein the frequency band with a reduction greater than -10dB is from 5.22-7.10GHz, and the -10dB relative bandwidth of RCS reduction is 47%, which is larger than the -10dB relative bandwidth of existing literature, and to a certain extent achieves the reduction of dual-station RCS within the working frequency band, providing a research basis for designing low-detectability radar systems.

[0029] The present invention achieves coherent cancellation of the antenna's overall scattering field by arranging two types of radiating units in a chessboard array, and disperses them to non-threatening angles, thereby achieving the antenna's broadband low radar cross-section characteristics. The present invention uses the antenna's radiating units as metasurface units that control the scattering field phase, achieving an integrated design of the metasurface structure and the antenna structure. While achieving broadband RCS reduction, the present invention ensures that the antenna's radiation performance within the working frequency band is not affected; the present invention has important application significance in the field of stealth antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a top view of the supersurface antenna array structure of the present invention.

[0031] Figure 2 It is a side view of the supersurface antenna array structure of the present invention.

[0032] Figure 3 It is a top view of the structure of the first rectangular patch unit in the metasurface antenna array of the present invention.

[0033] Figure 4 It is a top view of the structure of the second bidirectional comb-shaped patch unit in the metasurface antenna array of the present invention.

[0034] Figure 5 It is a comparison diagram of the reflection coefficients of the first rectangular patch unit and the second bidirectional comb-shaped patch unit in the metasurface antenna array of the present invention in the radiation and receiving states.

[0035] Figure 6 It is a comparison diagram of the yoz surface gains of the first rectangular patch unit and the second bidirectional comb-shaped patch unit in the metasurface antenna array of the present invention in the radiation and receiving states.

[0036] Figure 7a This is a comparison diagram of the reflection amplitudes of the first rectangular patch unit and the second bidirectional comb-shaped patch unit in the metasurface antenna array of the present invention under vertical incidence of TE waves.

[0037] Figure 7b This is a reflection phase comparison diagram of the first rectangular patch unit and the second bidirectional comb-shaped patch unit in the metasurface antenna array of the present invention under vertical incidence of TE waves.

[0038] Figure 8a This is a comparison diagram of the reflection amplitudes of the first rectangular patch unit and the second bidirectional comb-shaped patch unit in the metasurface antenna array of the present invention under vertical incidence of TM waves.

[0039] Figure 8b This is a reflection phase comparison diagram of the first rectangular patch unit and the second bidirectional comb-shaped patch unit in the metasurface antenna array of the present invention under vertical incidence of TM waves.

[0040] Fig. 9 1. A top view of two reference antennas of the metasurface antenna array of the present invention.

[0041] Fig.10 It is a comparison diagram of the reflection coefficient curves of the metasurface antenna array of the present invention and the reference antenna in the radiation and receiving states.

[0042] Fig.11 It is a comparison diagram of the yoz surface gain of the metasurface antenna array of the present invention and the reference antenna in the radiation and receiving states.

[0043] Fig.12 This is a comparison chart of the single-station RCS variation with frequency curves of the metasurface antenna array of the present invention and the reference antenna.

[0044] Fig.13 This is a comparison chart of the single-station RCS curves of the metasurface antenna array of the present invention and the reference antenna at 6.4 GHz as the incident angle changes.

[0045] Fig.14a It is the three-dimensional scattering pattern of reference antenna 1 at 6.4 GHz when a plane wave is incident vertically along the -z axis.

[0046] Fig.14b It is the three-dimensional scattering pattern of reference antenna 2 at 6.4 GHz when a plane wave is incident vertically along the -z axis.

[0047] Fig.14c It is the three-dimensional scattering pattern of the metasurface antenna array of the present invention at 6.4 GHz when a plane wave is incident vertically along the -z axis. DETAILED DESCRIPTION

[0048] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments and drawings. The contents mentioned in the implementation modes are not intended to limit the present invention.

[0049] Reference Figure 1 , Figure 2As shown in the example, a compact low RCS metasurface antenna array of the present invention comprises: 8 first rectangular patch units 1, 8 second bidirectional comb-tooth patch units 2, an intermediate dielectric layer 3, a metal backplane layer 4, and 8 first coaxial metal feed posts 5 and 8 second coaxial metal feed posts 6; the first rectangular patch units 1 and the second bidirectional comb-tooth patch units 2 are periodically printed and arranged on the upper surface of the intermediate dielectric layer 3 in a chessboard shape, and the metal backplane layer 4 is printed on the lower surface of the intermediate dielectric layer 3. Each first coaxial metal feed post 5 is located at c1 from the center of each first rectangular patch unit 1, and each second coaxial metal feed post 6 is located at c2 from the center of each second bidirectional comb-tooth patch unit 2. The intermediate dielectric layer 3 is made of 80mm*80mm*3mm material, which is F4B, with a dielectric constant of 2.65 and a loss tangent of 0.001. The metal backplane layer 4 is made of a conductive material with a conductivity of σ=5.8×10 7 S / m copper material, size is 80mm*80mm. The metal patch layer, the intermediate dielectric layer and the metal backplane layer are stacked seamlessly in order from top to bottom, and the present invention is taken but not limited to 4*4 units.

[0050] Reference Figure 3 The size of the first rectangular patch unit 1 is L1*W1, and the distance from the center c1 of the first rectangular patch unit 1 is the first metal feeding column 5, and the radius of the first metal feeding column 5 is 0.5 mm. Figure 4, the size of the second bidirectional comb-tooth patch unit 2 is L2*W2, and the comb-tooth structures are comb teeth 7, comb teeth 8, comb teeth 9, comb teeth 10, comb teeth 11, comb teeth 12, comb teeth 13 and comb teeth 14. The comb-tooth structure size is d*b, the comb teeth 7 is located 1.7mm below the upper edge of the second bidirectional comb-tooth patch unit 2 and is located on the left side of the second bidirectional comb-tooth patch unit 2, the comb teeth 8 is located 1.7mm below the upper edge of the second bidirectional comb-tooth patch unit 2 and is located on the right side of the second bidirectional comb-tooth patch unit 2, the comb teeth 9 are located 1.7mm below the lower edge of the comb teeth 7 and are located on the left side of the second bidirectional comb-tooth patch unit 2, the comb teeth 10 are located 1.7mm below the lower edge of the comb teeth 8 and are located on the second On the right side of the bidirectional comb-tooth patch unit 2, the comb teeth 11 are located 1.7 mm below the lower edge of the comb teeth 9 and on the left side of the second bidirectional comb-tooth patch unit 2, the comb teeth 12 are located 1.7 mm below the lower edge of the comb teeth 10 and on the right side of the second bidirectional comb-tooth patch unit 2, the comb teeth 13 are located 1.7 mm below the lower edge of the comb teeth 11 and on the left side of the second bidirectional comb-tooth patch unit 2, and the comb teeth 14 are located 1.7 mm below the lower edge of the comb teeth 12 and on the right side of the second bidirectional comb-tooth patch unit 2. The second metal feeding column 6 is located at a distance c2 from the center of the second bidirectional comb-tooth patch unit 2, and the radius of the second metal feeding column 6 is 0.5 mm.

[0051] A design method of a compact low RCS metasurface antenna array of the present invention comprises the following steps:

[0052] 1) Derived the size of the first rectangular patch unit according to the resonant frequency calculation formula of the antenna array, and determined the position of the metal feeding column of the first rectangular patch unit;

[0053] 2) According to the reflection phase of the first rectangular patch unit, the size of the second bidirectional comb-shaped patch unit is determined by adjusting its size, and the reflection phases of the two obtained satisfy a phase difference of 180°±37°;

[0054] 3) According to the size of the second bidirectional comb-shaped patch unit and the calculation formula of the resonant frequency of the antenna array, the theoretical radiation side electrical length of the second bidirectional comb-shaped patch unit and the position of the metal feeding post of the second bidirectional comb-shaped patch unit are derived;

[0055] 4) According to the theoretical radiation side electrical length and size of the second bidirectional comb-tooth patch unit, a comb-tooth structure is added to the radiation side of the second bidirectional comb-tooth patch unit so that the radiation side length reaches the theoretical radiation side electrical length, and the size and position of the comb-tooth structure of the second bidirectional comb-tooth patch unit are adjusted and determined;

[0056] 5) Select a processing material, use copper clad plate technology to periodically print a metal patch layer consisting of the above two patch units on the upper surface of the processing material, and print a metal backplane layer on the lower surface of the processing material to obtain the designed compact low RCS metasurface antenna array.

[0057] The calculation formula for the size of the first rectangular patch unit in step 1) is: The calculation formula for the position of the metal feeding column of the first rectangular patch unit is: Where W1 is the width of the radiation side of the first rectangular patch unit, L1 is the length of the radiation side of the first rectangular patch unit, c0 is the propagation speed of light in vacuum, f0 is the specified resonant center frequency, ε r is the relative dielectric constant of the intermediate dielectric layer, c1 is the distance between the metal feeding column of the first rectangular patch unit and the center of the first rectangular patch unit, and h is the thickness of the intermediate dielectric layer.

[0058] The specific steps of adjusting the size of the first rectangular patch unit in the step 2) are as follows: without changing the width of the first rectangular patch unit, increase / decrease the length of the first rectangular patch unit, and when the length of the second bidirectional comb-tooth patch unit is L2, the reflection amplitude within the wide band is reduced when the x-polarized wave is incident, and the reflection phase when the y-polarized wave is incident is not affected; without changing the length of the second bidirectional comb-tooth patch unit, increase / decrease the width of the second bidirectional comb-tooth patch unit, and when the length of the second bidirectional comb-tooth patch unit is W2, a phase difference of 180°±37° with the first rectangular patch unit is formed within the wide band when the y-polarized wave is incident, and the reflection amplitude of the incident x-polarized wave is not affected.

[0059] The formula for the theoretical radiation side electrical length of the second bidirectional comb-shaped patch unit derived in step 3) is: The calculation formula for the position of the metal feeding post of the second bidirectional comb-shaped patch unit is: Wherein, L2 is the actual length of the radiation side of the second bidirectional comb-tooth patch unit, L2′ is the theoretical radiation side electrical length of the second bidirectional comb-tooth patch unit, c0 is the propagation speed of light in vacuum, f0 is the specified resonant center frequency, ε r is the relative dielectric constant of the intermediate dielectric layer, c2 is the distance between the metal feeding column of the second bidirectional comb-tooth patch unit and the center of the second bidirectional comb-tooth patch unit, and h is the thickness of the intermediate dielectric layer.

[0060] The specific steps of step 4) adjusting the comb tooth structure size of the second bidirectional comb tooth patch unit are as follows: without changing the actual length L2 and width W2 of the second bidirectional comb tooth patch unit, four comb teeth are loaded at the radiation edge of the second bidirectional comb tooth patch unit respectively to increase / decrease the length and width of the comb teeth. When the length of the comb teeth is d and the width is b, L2′≈L2+4d is achieved. At this time, the working frequency band of the second bidirectional comb tooth patch unit as an antenna radiation unit is consistent with the working frequency band of the first rectangular patch unit as an antenna radiation unit. At the same time, it does not affect the reflection amplitude of the second bidirectional comb tooth patch unit when the x-polarized wave is incident and the reflection phase when the y-polarized wave is incident.

[0061] In this example, the commercial simulation software HFSS15.0 is used to optimize the specific parameters of the above antenna and fine-tune the radiation characteristics and scattering characteristics. The final parameters are shown in Table 1 below:

[0062] Table 1

[0063] parameter <![CDATA[L1]]> <![CDATA[W1]]> <![CDATA[L2]]> <![CDATA[W2]]> <![CDATA[c1]]> <![CDATA[c2]]> b d Numeric 12.5mm 13.1mm 10.4mm 9.5mm 3.2mm 1.4mm 0.3mm 2.8mm

[0064] For ease of understanding, the present invention is further described in conjunction with the following simulation results:

[0065] The reflection coefficients of the two patch units in the metasurface antenna array of the present invention in the radiation and receiving states are simulated and calculated. Figure 5 The simulation results show that the working frequency of the first rectangular patch unit 1 as the radiating unit antenna is 6.51GHz, and the working frequency of the second bidirectional comb-shaped patch unit 2 as the radiating unit antenna is 6.48GHz. Taking the reflection coefficient ≤-10dB as the standard, the working frequency band of the first rectangular patch unit 1 as the radiating unit antenna is 6.22-6.83GHz, and the working frequency band of the second bidirectional comb-shaped patch unit 2 as the radiating unit antenna is 6.26-6.68GHz. The reflection coefficients of the two patch units are basically the same. Figure 5 It can be seen that in the present invention, the resonance point and the working bandwidth of the antenna using the first rectangular patch unit 1 as the radiation unit antenna are basically the same as those of the antenna using the second bidirectional comb-shaped patch unit 2 as the radiation unit antenna.

[0066] The yoz surface gains of the two patch units in the metasurface antenna array of the present invention in the radiation and receiving states are simulated and calculated, referring to Figure 6The simulation results show that the difference in gain curves of the antenna on the yoz plane between the first rectangular patch unit 1 as the radiating unit antenna and the second bidirectional comb-shaped patch unit 2 as the radiating unit antenna is small, wherein the gain of the antenna on the yoz plane with the first rectangular patch unit 1 as the radiating unit antenna is 6.85dB, and the gain of the antenna on the yoz plane with the second bidirectional comb-shaped patch unit 2 as the radiating unit antenna is 6.65dB. This indicates that the directional patterns of the antenna on the yoz plane between the first rectangular patch unit 1 as the radiating unit antenna and the second bidirectional comb-shaped patch unit 2 as the radiating unit antenna are basically the same.

[0067] The reflection phase and amplitude of the two patch units in the metasurface antenna array of the present invention under vertical incidence of TE waves are simulated and calculated. Figure 7a and Figure 7b It can be seen that the reflection phase zero point of the first rectangular patch unit 1 as the radiation unit antenna and the second bidirectional comb-shaped patch unit 2 as the radiation unit antenna under vertical incidence of TE waves in the present invention is near 6.38 GHz, and the reflection phase curves of the two antennas under vertical incidence of TE waves are basically the same; the reflection amplitudes of the first rectangular patch unit 1 as the radiation unit antenna and the second bidirectional comb-shaped patch unit 2 as the radiation unit antenna under vertical incidence of TE waves are 0.29 and 0.32 near 6.38 GHz, and the reflection amplitudes of the two antennas under vertical incidence of TE waves are basically the same, both of which show good wave absorption characteristics.

[0068] The reflection phase and amplitude of the two patch units in the metasurface antenna array of the present invention under vertical incidence of TM waves are simulated and calculated. Figure 8a and Figure 8b It can be seen that the reflection phase of the first rectangular patch unit 1 as the radiating unit antenna and the second bidirectional comb-shaped patch unit 2 as the radiating unit antenna under vertical incidence of TM waves in the present invention achieves a phase difference that satisfies the phase cancellation condition (180±37°) in the 5.8-7.1GHz frequency band; the reflection amplitude of the first rectangular patch unit 1 as the radiating unit antenna and the second bidirectional comb-shaped patch unit 2 as the radiating unit antenna under vertical incidence of TM waves in the present invention are both near 1 in the calculated frequency band, showing a total reflection characteristic; the reflection amplitudes of the two antennas are basically consistent in the 5.8-7.1GHz frequency band under vertical incidence of TM waves, and the reflection phase satisfies the phase difference of the phase cancellation condition (180±37°), and the phase difference can enable the two antennas to achieve RCS reduction by utilizing phase cancellation through a chessboard structure arrangement when the TM wave is vertically incident.

[0069] Reference Fig. 9There are two reference antennas. The antenna radiation unit of the reference antenna 1 is arranged in a 4*4 printed manner by the first rectangular patch unit 1 in the metasurface antenna array of the present invention. The reference antenna 1 includes 4*4 first rectangular patch units 1, an intermediate dielectric layer 3, a metal backplane layer 4 and 4*4 first metal feeding posts 5. The first rectangular patch units 1 are periodically printed and arranged on the upper surface of the intermediate dielectric layer 3, and the metal backplane layer 4 is printed on the lower surface of the intermediate dielectric layer 3. Each first coaxial metal feeding post 5 is located 3.2 mm away from the center of each first rectangular patch unit 1. The intermediate dielectric layer 3 adopts a rectangular material of 80 mm*80 mm*3 mm, which is F4B, with a dielectric constant of 2.65 and a loss tangent of 0.001. The metal backplane layer 4 adopts a conductivity of σ=5.8×10 7 S / m copper material, size is 80mm*80mm. The metal patch layer, intermediate dielectric layer and metal backplane layer are all seamlessly stacked in sequence. The reference antenna 2 antenna radiation unit is arranged in a 4*4 printed manner by the second bidirectional comb-tooth patch unit 2 in the metasurface antenna of the present invention. The reference antenna 2 includes 4*4 second bidirectional comb-tooth patch units 2, an intermediate dielectric layer 3, a metal backplane layer 4 and 4*4 second coaxial metal feeding posts 6. The second bidirectional comb-tooth patch units 2 are periodically printed and arranged on the upper surface of the intermediate dielectric layer 3, and the metal backplane layer 4 is printed on the lower surface of the intermediate dielectric layer 3. Each second coaxial metal feeding post 6 is located 1.4mm away from the center of each second bidirectional comb-tooth patch unit 2. The intermediate dielectric layer 3 adopts a material of 80mm*80mm*3mm, which is F4B, with a dielectric constant of 2.65 and a loss tangent of 0.001. The metal backplane layer 4 adopts a conductivity of σ=5.8×10 7 S / m copper material, size is 80mm*80mm. The metal patch layer, the intermediate dielectric layer and the metal backplane layer are all seamlessly stacked in sequence.

[0070] The reflection coefficients of the metasurface antenna array and the reference antenna in the radiation and reception states are simulated and calculated. Fig.10 It can be seen that the working frequency of the metasurface antenna array of the present invention is 6.51 GHz, and the working frequencies of the two reference antennas are 6.48 GHz and 6.50 GHz respectively. Taking the reflection coefficient ≤ -10 dB as the standard, the working frequency band of the metasurface antenna array of the present invention is 6.22-6.83 GHz, and the working frequency bands of the two reference antennas are 6.26-6.68 GHz and 6.22-6.83 GHz respectively. The reflection coefficients of the three antennas are basically the same. Fig.10 It can be seen that the resonance point and working bandwidth of the metasurface antenna array in the present invention are basically the same as those of the reference antenna.

[0071] The yoz surface gain of the metasurface antenna array of the present invention and the reference antenna in the radiation and receiving states is simulated and calculated. Fig.11 It can be seen that the gain curves of the metasurface antenna array of the present invention on the yoz plane are relatively small compared with the two reference antennas, wherein the gain of the metasurface antenna array of the present invention on the yoz plane is 16.01dB, and the gain of the two reference antennas on the yoz plane is 16.10dB and 15.95dB, respectively. This indicates that the directional diagrams of the metasurface antenna array of the present invention on the yoz plane are basically the same as those of the reference antennas.

[0072] The above-mentioned single-station RCS variation curve of the metasurface antenna array of the present invention and the reference antenna is simulated and calculated, and the results are as follows: Fig.12 Compared with the reference antenna array, the metasurface antenna array of the present invention can achieve radar cross section reduction in a wide frequency band of 5.22-7.10 GHz, and the radar cross section reduction is greater than 10 dB in the frequency band of 5.22-7.10 GHz, indicating that the metasurface antenna array based on the chessboard structure of the present invention can significantly reduce the radar cross section of the antenna array, thereby achieving the stealth of the antenna.

[0073] The single-station RCS curves of the metasurface antenna array of the present invention and the reference antenna at 6.4 GHz are simulated and calculated as a function of the incident angle. The results are as follows: Fig.13 Compared with the reference antenna, the metasurface antenna array of the present invention can achieve radar cross section reduction within the angle range of -30 to 30 degrees of incident angle, and the radar cross section reduction is greater than 10dB within the angle range of -30 to 30 degrees, indicating that the present invention can significantly reduce the radar cross section of the antenna array, thereby achieving the stealth of the antenna.

[0074] The three-dimensional scattering patterns of the metasurface antenna array of the present invention and the reference antenna array under the condition of plane wave vertical incidence along the -z axis at 6.4 GHz are simulated and calculated. The results are as follows: Figure 14a-Figure 14c As shown, Fig.14a is the reference antenna 1, Fig.14b is the reference antenna 2, Fig.14c To design a metasurface antenna array. Compared with the reference antenna, the RCS of the metasurface antenna array of the present invention is significantly reduced along the main plane (XZ, YZ) under normal incidence, and the main reflection lobe points to four quadrants. At 6.4GHz, the RCS on the main plane of the metasurface antenna array of the present invention is reduced by 10.2dB compared with the reference antenna array. On the diagonal plane, the maximum RCS is 8.3dB smaller than that of the reference antenna. This reduction is because the reflection field is redirected to four main lobes instead of a single main lobe on the reference antenna surface. This shows that the metasurface antenna array of the present invention can greatly reduce the radar scattering cross section of the antenna array, thereby achieving the stealth of the antenna.

[0075] The present invention has many specific application paths. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements can be made without departing from the principle of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims

1. A compact low RCS metasurface antenna array, characterized in that: include: A metal patch layer, an intermediate dielectric layer, a metal backplane layer and a plurality of coaxial metal feed posts, wherein the metal patch layer, the intermediate dielectric layer and the metal backplane layer are seamlessly stacked in sequence from top to bottom; and the plurality of coaxial metal feed posts respectively penetrate the metal patch layer, the intermediate dielectric layer and the metal backplane layer; The metal patch layer includes a first rectangular patch unit and a second bidirectional comb-tooth patch unit, wherein the first rectangular patch unit is a rectangular patch with a regular shape, and the second bidirectional comb-tooth patch unit is a bidirectional comb-tooth patch with eight comb-tooth structures loaded on both sides of the radiation edge after the size of the first rectangular patch unit is adjusted; The reflection phase difference between the first rectangular patch unit and the second bidirectional comb-shaped patch unit satisfies 180°±37°, and they are printed and arranged in a 4*4 period on the middle dielectric layer in a checkerboard structure; The intermediate dielectric layer is made of a material of 80mm*80mm*3mm, which is an F4B substrate with a dielectric constant of 2.65 and a loss tangent of 0.

001.

2. The compact low RCS metasurface antenna array according to claim 1, characterized in that: Assuming that the antenna array includes 4*4 patch units, it has 4*4 feeding points accordingly, and the 4*4 feeding points are regularly arranged below the 4*4 patch units.

3. The compact low RCS metasurface antenna array according to claim 1, characterized in that: The metal back plate layer has a conductivity of σ=5.8×10 7 S / m copper material, size is 80mm*80mm.

4. A design method for a compact low RCS metasurface antenna array, based on the compact low RCS metasurface antenna array of claim 1, characterized in that: The steps include: 1) Derived the size of the first rectangular patch unit according to the resonant frequency calculation formula of the antenna array, and determined the position of the metal feeding column of the first rectangular patch unit; 2) According to the reflection phase of the first rectangular patch unit, the size of the second bidirectional comb-shaped patch unit is determined by adjusting its size, and the reflection phases of the two obtained satisfy a phase difference of 180°±37°; 3) According to the size of the second bidirectional comb-shaped patch unit and the calculation formula of the resonant frequency of the antenna array, the theoretical radiation side electrical length of the second bidirectional comb-shaped patch unit and the position of the metal feeding post of the second bidirectional comb-shaped patch unit are derived; 4) According to the theoretical radiation side electrical length and size of the second bidirectional comb-tooth patch unit, a comb-tooth structure is added to the radiation side of the second bidirectional comb-tooth patch unit so that the radiation side length reaches the theoretical radiation side electrical length, and the size and position of the comb-tooth structure of the second bidirectional comb-tooth patch unit are adjusted and determined; 5) Select a processing material, use copper clad plate technology to periodically print a metal patch layer consisting of the above two patch units on the upper surface of the processing material, and print a metal backplane layer on the lower surface of the processing material to obtain the designed compact low RCS metasurface antenna array.

5. The design method of a compact low RCS metasurface antenna array according to claim 4, characterized in that: The calculation formula for the size of the first rectangular patch unit in step 1) is: The calculation formula for the position of the metal feeding column of the first rectangular patch unit is: Where W1 is the width of the radiation side of the first rectangular patch unit, L1 is the length of the radiation side of the first rectangular patch unit, c0 is the propagation speed of light in vacuum, f0 is the specified resonant center frequency, ε r is the relative dielectric constant of the intermediate dielectric layer, c1 is the distance between the metal feeding column of the first rectangular patch unit and the center of the first rectangular patch unit, and h is the thickness of the intermediate dielectric layer.

6. The design method of a compact low RCS metasurface antenna array according to claim 4, characterized in that: The specific steps of adjusting the size of the first rectangular patch unit in the step 2) are as follows: without changing the width of the first rectangular patch unit, increase / decrease the length of the first rectangular patch unit, and when the length of the second bidirectional comb-tooth patch unit is L2, the reflection amplitude within the wide band is reduced when the x-polarized wave is incident, and the reflection phase when the y-polarized wave is incident is not affected; without changing the length of the second bidirectional comb-tooth patch unit, increase / decrease the width of the second bidirectional comb-tooth patch unit, and when the length of the second bidirectional comb-tooth patch unit is W2, a phase difference of 180°±37° with the first rectangular patch unit is formed within the wide band when the y-polarized wave is incident, and the reflection amplitude of the incident x-polarized wave is not affected.

7. The design method of a compact low RCS metasurface antenna array according to claim 4, characterized in that: The formula for the theoretical radiation side electrical length of the second bidirectional comb-shaped patch unit derived in step 3) is: The calculation formula for the position of the metal feeding post of the second bidirectional comb-shaped patch unit is: Wherein, L2 is the actual length of the radiation side of the second bidirectional comb-tooth patch unit, L2′ is the theoretical radiation side electrical length of the second bidirectional comb-tooth patch unit, c0 is the propagation speed of light in vacuum, f0 is the specified resonant center frequency, ε r is the relative dielectric constant of the intermediate dielectric layer, c2 is the distance between the metal feeding column of the second bidirectional comb-tooth patch unit and the center of the second bidirectional comb-tooth patch unit, and h is the thickness of the intermediate dielectric layer.

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