Wideband circularly polarized metasurface antenna with in-band and out-of-band radar cross section reduction

Abstract

The application discloses a broadband circularly polarized metasurface antenna with in-band and out-of-band radar cross section reduction, comprising: an upper layer structure with a metasurface and a lower layer structure with a feed network, the upper layer structure and the lower layer structure being connected through an adhesive layer formed by RO4450F prepreg of a middle layer; the upper layer structure comprises: a metasurface metal patch, a first dielectric substrate and a metal ground plate connected from top to bottom; 16 unit structures are arranged to form a metasurface, and each unit metal patch comprises: a C-shaped metal patch, a circular metal patch and an L-shaped metal patch; the lower layer structure comprises a second dielectric substrate and a feed network; a short-circuit needle and a feed probe are connected with the circular metal patch and the metal ground plate and the feed network respectively. The technical scheme has the characteristics of wideband left-handed circular polarization radiation and low profile, and simultaneously has the in-band and out-of-band radar cross section reduction performance in the antenna operating bandwidth.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of antennas, and particularly relates to a broadband circularly polarized metasurface antenna with reduced radar cross section (RCS) in-band and out-of-band. BACKGROUND

[0002] Antennas are key components in modern military communication systems. With the advancement of radar detection technology, stealth technology has become increasingly important. However, traditional antenna designs often become the main detection targets of enemy radars due to their metallic structures and open radiation characteristics. Therefore, how to reduce the radar cross section (RCS) of the main scattering source, i.e., the antenna, while maintaining its radiation performance, has become an important issue.

[0003] Antenna RCS reduction methods mainly include artificial magnetic conductor (AMC), loading absorber, and P-B phase technology. Among them, the RCS reduction mechanism of artificial magnetic conductor is mainly through its reflection phase and metal phase difference of 180°±37°, achieving phase cancellation at a specific frequency, thereby significantly reducing the antenna RCS. This method has a relatively simple structure, but the bandwidth is limited, and it is usually effective only in a narrow band. The loading absorber method is to introduce electromagnetic absorbing materials or metamaterial structures to dissipate the incident energy into heat energy, suppressing electromagnetic wave reflection. This method has good RCS reduction effect, but the overall profile is large, which is not conducive to integration. The RCS reduction method based on P-B phase mainly relies on introducing geometric phase control on the unit structure, so that the scattering waves of different units are directionally redistributed in space, thereby reducing the scattering energy in a certain direction. This method has good wideband characteristics and polarization adaptability, but it has high requirements for phase accuracy and array arrangement in actual design. At present, although the above-mentioned technologies can achieve different degrees of RCS reduction, there is still a balance challenge between wideband RCS reduction, antenna radiation performance, profile height, and design complexity. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a broadband circularly polarized metasurface antenna with reduced radar cross section (RCS) in-band and out-of-band.

[0005] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0006] A broadband circularly polarized metasurface antenna with reduced radar cross section (RCS) in-band and out-of-band, comprising: an upper layer structure with a metasurface and a lower layer structure with a feed network, the upper layer structure and the lower layer structure being connected by an adhesive layer composed of RO4450F semi-cured sheets in the middle layer.

[0007] As preferred, the upper structure comprises: a super surface metal patch, a first dielectric substrate and a metal ground plate connected from top to bottom; 16 unit structures are arranged into a super surface with 4*4 unit groups, each metal patch of the unit structure comprises: a C-shaped metal patch, a circular metal patch and an L-shaped metal patch, and the C-shaped metal patch, the circular metal patch and the L-shaped metal patch are not connected with each other; a short-circuit needle connects the circular metal patch and the metal ground plate, and a feed probe connects the circular metal patch and a feed network.

[0008] As preferred, the lower structure comprises: a second dielectric substrate, a 1 / 16 broadband sequential rotation feed network is arranged on the second dielectric substrate; the feed network comprises: a 180-degree phase shifter, a first 90-degree phase shifter, a second 90-degree phase shifter, a first Wilkinson power divider, a second Wilkinson power divider, a third Wilkinson power divider, eight T-shaped power dividers and a microstrip transmission line; wherein the feed network is connected with an input and output end of external signals through the microstrip transmission line, and the microstrip transmission line is connected with the first Wilkinson power divider; the first Wilkinson power divider is connected with the 180-degree phase shifter and a 180-degree reference microstrip line corresponding to the 180-degree phase shifter through two mirror-symmetrical curved microstrip lines; the 180-degree phase shifter and the 180-degree reference microstrip line are connected with the second Wilkinson power divider and the third Wilkinson power divider respectively; the second Wilkinson power divider is connected with the first 90-degree phase shifter and a first 90-degree reference microstrip line corresponding to the first 90-degree phase shifter respectively; the first 90-degree phase shifter and the first 90-degree reference microstrip line are connected with four T-shaped power dividers respectively; the third Wilkinson power divider is connected with the second 90-degree phase shifter and a second 90-degree reference microstrip line corresponding to the second 90-degree phase shifter respectively, and the second 90-degree phase shifter and the second 90-degree reference microstrip line are connected with four T-shaped power dividers respectively.

[0009] As preferred, the first dielectric substrate is an F4BM265 dielectric substrate with h1=3mm.

[0010] As preferred, the second dielectric substrate is an F4BM265 dielectric substrate with h3=0.1mm.

[0011] As preferred, the adhesive layer is an RO4450F prepreg with h2=0.2mm.

[0012] As preferred, the thickness of the C-shaped metal patch, the circular metal patch and the L-shaped metal patch is 0.018mm, and all the metal materials are copper.

[0013] The technical scheme of the present application has the characteristics of wideband left-handed circularly polarized radiation and low profile, and simultaneously has the performance of reducing radar scattering cross section in the band and out of the band of the antenna working bandwidth. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only are the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on the provided drawings.

[0015] Figure 1 Structure diagram of the wideband circularly polarized metasurface antenna with in-band and out-of-band radar cross section reduction in the embodiments of the present application;

[0016] Figure 2 Structure diagram of the unit; wherein, Figure 2 (a) is a three-dimensional assembly structure diagram of the unit, Figure 2 (b) is a top view structure diagram of the unit;

[0017] Figure 3 Simulation radiation performance diagram of the unit; wherein, Figure 3 (a) is a |S 11 performance curve diagram of the unit radiation changing with frequency, Figure 3 (b) is a gain change curve diagram of the unit radiation changing with frequency;

[0018] Figure 4 Simulation polarization conversion performance diagram of the unit; wherein, Figure 4 (a) is a co-polarization and cross-polarization reflection amplitude performance curve diagram of the unit, Figure 4 (b) is a polarization conversion rate performance curve diagram of the unit;

[0019] Figure 5 Planar structure view of the metasurface antenna; wherein, Figure 5 (a) is a planar structure view of the upper layer 16 units of the metasurface antenna; Figure 5 (b) is a planar structure view of the 1 / 16 feeding network of the lower layer of the metasurface antenna;

[0020] Figure 6 Three-dimensional assembly structure diagram of the 90-degree phase shifter used by the feeding network;

[0021] Figure 7 Three-dimensional assembly structure diagram of the 180-degree phase shifter used by the feeding network;

[0022] Figure 8 First 90-degree reference microstrip line used by the feeding network;

[0023] Figure 9 Second 90-degree reference microstrip line used by the feeding network;

[0024] Figure 10A 180-degree reference microstrip line for use in the feed network;

[0025] Figure 11 A plan view of a Wilkinson power divider for use in the feed network;

[0026] Figure 12 A schematic diagram of a T-shaped power divider for use in the feed network;

[0027] Figure 13 Simulation performance of the feed network; wherein, Figure 13 (a) a plot of S-parameters of the feed network, Figure 13 (b) a plot of phase difference between adjacent ports of the feed network;

[0028] Figure 14 Simulation radiation performance of the metasurface antenna; wherein, Figure 14 (a) a plot of |S 11 performance of the metasurface antenna, Figure 14 (b) a plot of axial ratio performance of the metasurface antenna, Figure 14 (c) a plot of gain performance of the metasurface antenna, Figure 14 (d) a plot of efficiency performance of the metasurface antenna;

[0029] Figure 15 Simulation normalized radiation patterns of the metasurface antenna; wherein, Figure 15 (a) and Figure 15 (b) are respectively the normalized radiation pattern in the xoz plane and the yoz plane of the metasurface antenna at 9 GHz, Figure 15 (c) and Figure 15 (d) are respectively the normalized radiation pattern in the xoz plane and the yoz plane of the metasurface antenna at 10 GHz, Figure 15 (e) and Figure 15 (f) are respectively the normalized radiation pattern in the xoz plane and the yoz plane of the metasurface antenna at 11 GHz, Figure 15 (g) and Figure 15 (h) are respectively the normalized radiation pattern in the xoz plane and the yoz plane of the metasurface antenna at 12 GHz;

[0030] Figure 16 Simulation single station RCS reduction performance of the metasurface antenna. DETAILED DESCRIPTION

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Example 1:

[0034] like Figure 1 As shown, an embodiment of the present invention provides a broadband circularly polarized metasurface antenna with reduced in-band and out-of-band radar cross-section, comprising: an upper structure with a metasurface and a lower structure with a feed network, wherein the upper structure and the lower structure are connected by an adhesive layer composed of an RO4450F prepreg with a height of h2 = 3 mm in the middle layer.

[0035] In one embodiment of the present invention, the upper structure includes: a metasurface metal patch, a first dielectric substrate, and a metal ground plane connected from top to bottom, wherein the first dielectric substrate is an F4BM265 dielectric substrate with h1 = 3mm, and the relative permittivity ε of the F4BM265 dielectric substrate is... r =2.65, loss tangent tanδ = 0.0013; 16 unit structures are arranged into 4×4 units to form a metasurface. The metal patches of each unit include: C-shaped metal patch, circular metal patch, and L-shaped metal patch, and the C-shaped metal patch, circular metal patch, and L-shaped metal patch are not connected to each other; shorting pin connects the circular metal patch to the metal ground plane, and feeding probe connects the circular metal patch to the feeding network; the thickness of the C-shaped metal patch, circular metal patch, and L-shaped metal patch is 0.018mm, and all metal materials are copper.

[0036] In one embodiment of the present invention, the lower layer structure includes: a second dielectric substrate, on which a 1 / 16 broadband sequential rotating feed network is provided; the second dielectric substrate is an F4BM265 dielectric substrate with h3 = 0.1 mm, and the relative permittivity ε of the F4BM265 dielectric substrate is... r= 2.65, loss tangent tan delta = 0.0013; the feeding network comprises: a 180-degree phase shifter, a first 90-degree phase shifter, a second 90-degree phase shifter, a first Wilkinson power divider, a second Wilkinson power divider, a third Wilkinson power divider, eight T-shaped power dividers, and a microstrip transmission line; wherein the feeding network is connected with input and output ends of external signals through the microstrip transmission line, the microstrip transmission line is connected with the first Wilkinson power divider; the first Wilkinson power divider is connected with the 180-degree phase shifter and a reference microstrip line corresponding to the 180-degree phase shifter (hereinafter referred to as a 180-degree reference microstrip line) through two segments of mirror-symmetrical curved microstrip lines. The 180-degree phase shifter and the 180-degree reference microstrip line are further connected with the second Wilkinson power divider and the third Wilkinson power divider, respectively; the second Wilkinson power divider is connected with the first 90-degree phase shifter and a reference microstrip line corresponding to the first 90-degree phase shifter (hereinafter referred to as a first 90-degree reference microstrip line). The first 90-degree phase shifter and the first 90-degree reference microstrip line are further connected with four T-shaped power dividers, respectively; similarly, the third Wilkinson power divider is connected with the second 90-degree phase shifter and a reference microstrip line corresponding to the second 90-degree phase shifter (hereinafter referred to as a second 90-degree reference microstrip line). The second 90-degree phase shifter and the second 90-degree reference microstrip line are further connected with four T-shaped power dividers, respectively.

[0037] In an embodiment of the present application, as shown in Figure 2 FIG. 1 is a structural diagram of a unit. Figure 2 (a) is a perspective assembly structural diagram of the unit, Figure 2 (b) is a top view structural diagram of the unit. The unit structure period size p = 13 mm, the dielectric substrate thickness h1 = 1 mm, the feeding probe diameter d1 = 0.7 mm, the short-circuit needle diameter d2 = 0.4 mm, the circular metal patch diameter d3 = 3.4 mm, the circular hollow diameter d4 = 1.4 mm left by the feeding probe in the metal ground plate, the length of the short straight edge of the C-shaped metal patch parallel to the v direction l1 = 0.7 mm, the length of the long straight edge parallel to the x direction and the y direction l2 = 6.6 mm, the L-shaped metal patch length l3 = 3.4 mm, the vertical distance l4 = 3.7 mm from the center of the feeding probe to the nearest unit boundary, the distance l5 = 0.9 mm between the center of the feeding probe and the center of the short-circuit needle in the y direction, the L-shaped metal patch width w1 = 0.9 mm, and the gap width w2 = 0.8 mm between the circular metal patch and the C-shaped metal patch.

[0038] In an embodiment of the present application, as shown in Figure 3 FIG. 4 is a simulation radiation performance of the unit. Figure 3 (a) is a |S 11 performance curve of the unit radiation with frequency variation, and it can be seen that the |S 11| Less than -10 dB from 8.3 to 12.7 GHz, indicating that the unit has good impedance matching in a wide frequency range. Figure 3 (b) is the gain variation curve of the unit radiation with frequency, and it can be seen that the unit has a maximum gain of 5.8 dBi at 11 GHz.

[0039] In an embodiment of the present application, as shown in Figure 4 , the simulation polarization conversion performance of the unit is shown. Figure 4 (a) is the co-polarization and cross-polarization reflection amplitude performance curve of the unit, where r xy represents the proportion of the reflected wave that is x-polarized when the y-polarized wave is vertically incident, and the definition is r xy = |E rx | / |E iy |, and r yy represents the proportion of the reflected wave that is y-polarized when the y-polarized wave is vertically incident, and the definition is r yy = |E ry | / |E iy |, r yx represents the proportion of the reflected wave that is y-polarized when the x-polarized wave is vertically incident, and the definition is r yx = |E ry | / |E ix |, and r xx represents the proportion of the reflected wave that is x-polarized when the x-polarized wave is vertically incident, and the definition is r xx = |E rx | / |E ix |, and it can be seen that the co-polarization and cross-polarization reflection amplitudes of the unit are consistent in the cases of x-polarized wave vertical incidence and y-polarized wave vertical incidence. Figure 4 (b) is the polarization conversion rate performance curve of the unit, and the polarization conversion rate is defined as or The polarization conversion rate is used to measure the polarization conversion capability of a structure. It can be seen that the polarization conversion rate of the unit is greater than 80% in a wide frequency range of 7.8-17 GHz.

[0040] In an embodiment of the present application, as shown in Figure 5 , a planar structure view of the metasurface antenna is shown. Figure 5 (a) is a planar structure view of the upper layer 16 units of the metasurface antenna, and it can be seen that the arrangement of the 16 units is a 2x2, i.e. 4-unit subarray, which is rotated around the center point of the entire metasurface to obtain a 4x4 chessboard arrangement. Such an arrangement can not only provide the necessary 90-degree spatial phase compensation for circularly polarized radiation, but also realize single-station RCS reduction through phase cancellation of scattered waves between 2x2 subarrays. Figure 5(b) is a plan view of a 1 / 16 feed network for the lower layer of the metasurface antenna, port 1 is the input port, ports 2, 3, 4, 5 output power substantially equal in the operating frequency band of 7.4-15.8 GHz, and the phase difference between adjacent ports is close to 90 degrees, through the first Wilkinson power divider, the second Wilkinson power divider, the third Wilkinson power divider, the 180-degree phase shifter, the 180-degree reference microstrip line, the first 90-degree phase shifter, the first 90-degree reference microstrip line, the second 90-degree phase shifter, the second 90-degree reference microstrip line, eight T-shaped power dividers, and the microstrip lines connecting them as shown.

[0041] In an embodiment of the present application, as shown in Figure 6 , is a perspective assembly structure diagram of a 90-degree phase shifter used by the feed network. The 90-degree phase shifter is composed of two layers of metal patches in the z-axis direction, i.e. vertically opposite. The upper layer includes two rectangular metal patches, both with a length of l ps90 = 4.4 mm and a width of w ps90 = 0.4 mm, and the gap width between the two rectangular metal patches is w gap90 = 0.2 mm. The lower layer includes only one rectangular metal patch with a length l rec90 = 7.3 mm and a width w ps90 = 0.4 mm. The midpoint of the gap between the two rectangular metal patches in the upper layer is opposite the midpoint of the rectangular metal patch in the lower layer. In this figure, the structure with a thickness of h3 = 0.1 mm is the second dielectric substrate in the overall structure, and the structure with a thickness of h2 = 0.2 mm is the adhesive layer in the overall structure.

[0042] In an embodiment of the present application, as shown in Figure 7 , is a perspective assembly structure diagram of a 180-degree phase shifter used by the feed network. The 180-degree phase shifter is composed of two layers of metal patches in the z-axis direction, i.e. vertically opposite. The upper layer includes three rectangular metal patches, the two shorter rectangular metal patches on the sides are the same size, both with a length of l ps180 = 4.4 mm and a width of w ps180 = 0.4 mm, and the longer rectangular metal patch in the middle has a width w ps180 = 0.4 mm, and the gap width between the longer rectangular metal patch and the two shorter rectangular metal patches is w gap180 = 0.2 mm. The lower layer includes two rectangular metal patches of the same size, both with a length l rec90 = 7 mm and a width w ps180=0.4mm. The two midpoints of the two gaps between the three rectangular metal patches on the upper layer are respectively aligned with the two midpoints of the two rectangular metal patches on the lower layer. In this figure, the structure with a thickness of h3 = 0.1mm is the second dielectric substrate in the overall structure, and the structure with a thickness of h2 = 0.2mm is the adhesive layer in the overall structure.

[0043] In one embodiment of the present invention, such as Figure 8 The image shows the first 90-degree reference microstrip line used in the feed network. The first 90-degree reference microstrip line consists of five segments, each with a width of w. line Composed of microstrip lines with a length of 0.75 mm, the first segment of the microstrip line has a length of l. 90d11 =2mm, length l of the second microstrip line 90d12 =0.9mm, length l of the third microstrip line 90d13 = 5.3mm, length l of the fourth microstrip line 90d14 =0.9mm, length l of the fifth microstrip line 90d15 =2mm, and a 45-degree chamfer is added at each microstrip corner.

[0044] In one embodiment of the present invention, such as Figure 9 As shown, this is the second 90-degree reference microstrip line used in the feed network. The second 90-degree reference microstrip line consists of five segments, each with a width of w. line Composed of microstrip lines with a length of 0.75 mm, the first segment of the microstrip line has a length of l. 90d21 =2mm, length l of the second microstrip line 90d22 = 3.4mm, length l of the third microstrip line 90d23 = 4.2mm, length l of the fourth microstrip line 90d24 = 3.4mm, length l of the fifth microstrip line 90d25 =2mm, and a 45-degree chamfer is added at each microstrip corner.

[0045] In one embodiment of the present invention, such as Figure 10 As shown, this is the 180-degree reference microstrip line used in the power supply network. The 180-degree reference microstrip line consists of nine segments, each with a width of w. line Composed of microstrip lines with a length of 0.75 mm, the first segment of the microstrip line has a length of l. 180d1 =6mm, length l of the second microstrip line 180d2 =0.6mm, length l of the third microstrip line 180d3 =4mm, length l of the fourth microstrip line 180d4 =0.6mm, length l of the fifth microstrip line 180d5 =1.3mm, length l of the sixth microstrip line 180d6 = 2.4mm, the length of the seventh microstrip line l 180d7 = 3.1mm, length l of the eighth microstrip line180d8 = 2.4mm, length l of the ninth microstrip line 180d9 =1mm, and a 45-degree chamfer is added at each microstrip corner.

[0046] In one embodiment of the present invention, such as Figure 11 The image shows a plan view of the Wilkinson power divider used in the feeder network. This Wilkinson power divider is a second-order Wilkinson power divider. Each order Wilkinson power divider consists of three microstrip lines and one resistor. Except for the contact point between the resistor and the microstrip line, each microstrip line corner is chamfered at a 45-degree angle. Two orders Wilkinson power dividers are connected by two parallel microstrip lines. The width of each microstrip line in the first-order Wilkinson power divider is wpd1 = 0.65 mm, and the length of the first microstrip line in the first-order Wilkinson power divider is l. 11 =1.55mm, the length l of the second microstrip line in a first-order Wilkinson power divider. 12 =2.4mm, the length l of the third microstrip line in a first-order Wilkinson power divider 13 =1.4mm, the resistor corresponding to the first-order Wilkinson power divider is a 0603 package size, and the resistance value is R1 = 240Ω. The length of the first microstrip line of the second-order Wilkinson power divider is l. 21 =1.6mm, the length l of the second microstrip line in the second-order Wilkinson power divider 22 =1.6mm, the length l of the third microstrip line in the second-order Wilkinson power divider 23 =1.1mm, the resistor corresponding to the second-order Wilkinson power divider is a 0603 package size, and the resistance value R2 = 100Ω. The two parallel microstrip lines connecting the first-order and second-order Wilkinson power dividers both have a width of w. pdm =0.5mm, length is l pdm =0.9mm. The corresponding line widths at the input, output 1, and output 2 terminals of this Wilkinson power divider are all w. line =0.75mm.

[0047] In one embodiment of the present invention, such as Figure 12 The image shows a T-shaped power divider used in a power supply network. This T-shaped power divider consists of five rectangular microstrip lines and two annular metal rings. The width of the first microstrip line is w. t =0.4mm and length l t1 = 4.8mm, width w of the second microstrip line line =0.75mm and length l t2 =1.1mm, the width of the microstrip line in the third and fourth segments is w t =0.4mm and all lengths are l t3=5.6mm, and each rectangular microstrip line has a 45-degree chamfer at the corner. The inner diameter of both annular metal rings is d1 = 0.7mm, and the outer diameter is d... t =1.1mm.

[0048] In one embodiment of the present invention, such as Figure 13 The figure shows the simulation performance of the power supply network. Figure 13 (a) shows the S-parameter curves of the feeder network, |S 11 |、|S 21 |、|S 31 |、|S 41 |、|S 51 | represents the return loss at ports 1, 2, 3, 4, and 5 respectively, with input at port 1. It can be seen that |S 11 |Below -10dB in a wide bandwidth of 7.4–15.8GHz,|S 21 |、|S 31 |、|S 41 |、|S 51 The values ​​are essentially equal and close to -6dB across a wide bandwidth of 7.4–15.8 GHz. Figure 13 (b) shows the phase difference between adjacent ports of the feeder network. S can be seen... 31 With S 21 phase difference, S 41 With S 31 phase difference, S 51 With S 41 phase difference, S 21 With S 51 The phase difference is essentially equal and close to 90° over a wide frequency band of 7.4–15.8 GHz. Figure 13 (a) and Figure 13 (b) shows that the feed network has the characteristic of sequential rotation over a wide bandwidth, which is an important basis for the wideband left-hand circular polarization radiation characteristics of the metasurface antenna.

[0049] In one embodiment of the present invention, such as Figure 14 The figure shows the simulated radiation performance of the metasurface antenna. Figure 14 (a) is the |S| of the metasurface antenna. 11 The performance curve shows the S-value of this metasurface antenna. 11 The bandwidth less than -10dB, i.e., the impedance bandwidth, is 86% (6.5–16.3GHz). Figure 14 (b) shows the axial ratio performance curve of the metasurface antenna. It can be seen that the axial ratio of the metasurface antenna is less than 3dB, that is, the axial ratio bandwidth is 65.5% (7.4–14.6GHz). Figure 14(c) is the gain performance curve of the metasurface antenna, it can be seen that the gain of the metasurface antenna decreases from the maximum value by less than 3 dB, and the gain bandwidth is 49.3% (8.4-13.9 GHz). Taking the intersection part of the impedance bandwidth, the axial ratio bandwidth and the gain bandwidth, the working bandwidth of the metasurface antenna is 49.3% (8.4-13.9 GHz), and the maximum gain is 14.6 dBic. Figure 14 (d) is the efficiency curve of the metasurface antenna, including the radiation efficiency and the overall efficiency, the ranges of the radiation efficiency and the overall efficiency in the working bandwidth of 8.4-13.9 GHz are 69.3%-85.3% and 68.5%-84.8% respectively, which indicates that the antenna maintains a high efficiency in the wideband working bandwidth.

[0050] In an embodiment of the present application, as shown in Figure 15 , the simulation normalized radiation patterns of the metasurface antenna are shown. Figure 15 (a) and Figure 15 (b) are respectively the xoz-plane normalized radiation pattern and the yoz-plane normalized radiation pattern of the metasurface antenna at 9 GHz. Figure 15 (c) and Figure 15 (d) are respectively the xoz-plane normalized radiation pattern and the yoz-plane normalized radiation pattern of the metasurface antenna at 10 GHz. Figure 15 (e) and Figure 15 (f) are respectively the xoz-plane normalized radiation pattern and the yoz-plane normalized radiation pattern of the metasurface antenna at 11 GHz. Figure 15 (g) and Figure 15 (h) are respectively the xoz-plane normalized radiation pattern and the yoz-plane normalized radiation pattern of the metasurface antenna at 12 GHz. The solid lines in the above normalized radiation patterns represent the radiation pattern of left-handed circular polarization, and the dashed lines represent the radiation pattern of right-handed circular polarization. It can be seen that the main polarization, i.e. the radiation pattern of left-handed circular polarization, of the metasurface antenna is focused and stable in the boresight direction, and the metasurface antenna has good polarization isolation in a wide frequency band range in the boresight direction, in addition, the metasurface antenna also has a low sidelobe. The above simulation results show that the metasurface antenna has the characteristics of wideband left-handed circular polarization radiation.

[0051] In an embodiment of the present application, as shown in Figure 16The simulation single station RCS reduction performance of the metasurface antenna is shown. The solid line and the dashed line in the figure respectively represent the case of x-polarized wave vertical incidence and y-polarized wave vertical incidence. It can be seen that for the case of x-polarized wave vertical incidence, the bandwidth of the single station RCS reduction of the metasurface antenna to the single station RCS of the metal floor with the same size is greater than 10 dB, which is 71.3% (8.3-17.5 GHz); for the case of y-polarized wave vertical incidence, the bandwidth of the single station RCS reduction of the metasurface antenna to the single station RCS of the metal floor with the same size is greater than 10 dB, which is 71.9% (8.1-17.2 GHz). It can be seen from the simulation results that the single station 10 dB RCS reduction bandwidth of the metasurface antenna for x-polarized wave vertical incidence and y-polarized wave vertical incidence both contain all the in-band and part of the out-of-band of the antenna operating bandwidth, proving that the metasurface antenna has the in-band and out-of-band RCS reduction performance.

[0052] The metasurface antenna disclosed in the present application has the characteristics of wideband left-handed circularly polarized radiation, in-band and out-of-band RCS reduction, low profile and simple design, and has potential application in future stealth communication platforms.

[0053] The above-described embodiments are only descriptions of the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A broadband circularly polarized metasurface antenna with reduced in-band and out-of-band radar cross-section, characterized in that, include: The upper structure has a metasurface and the lower structure has a power supply network. The upper and lower structures are bonded together by an adhesive layer consisting of an RO4450F prepreg in the middle layer. The upper structure includes: a metasurface metal patch, a first dielectric substrate, and a metal ground plane connected from top to bottom; 16 unit structures are arranged in a 4×4 unit configuration to form the metasurface, the 16 unit structures forming a checkerboard pattern, the 16 unit structures including four 2×2 subarrays, with one subarray as the first subarray, and each subsequent subarray rotating relative to the previous subarray with the metasurface center as the origin; each unit structure in the first subarray has a circular metal patch, a C-shaped metal patch, and an L-shaped metal patch arranged sequentially from the direction away from the metasurface center to the direction closer to the metasurface center, and the metal patches are not connected to each other; the opening of the C-shaped metal patch faces the circular metal patch, and the L-shaped metal patch is located on the side facing the metasurface center; a shorting pin connects the circular metal patch and the metal ground plane, and a power supply probe connects the circular metal patch and the power supply network; The lower layer structure includes: a second dielectric substrate, on which a 1 / 16 broadband sequential rotating power supply network is provided; the power supply network includes: a 180-degree phase shifter, a first 90-degree phase shifter, a second 90-degree phase shifter, a first Wilkinson power divider, a second Wilkinson power divider, a third Wilkinson power divider, eight T-shaped power dividers, and microstrip transmission lines; wherein, the power supply network is connected to the input and output terminals of external signals through the microstrip transmission lines, and the microstrip transmission lines are connected to the first Wilkinson power divider; the first Wilkinson power divider is connected to the 180-degree phase shifter and the corresponding 180-degree phase shifter through two mirror-symmetrical curved microstrip lines respectively. The reference microstrip line is connected; the 180-degree phase shifter and the 180-degree reference microstrip line are respectively connected to the second Wilkinson power divider and the third Wilkinson power divider; the second Wilkinson power divider is respectively connected to the first 90-degree phase shifter and the first 90-degree reference microstrip line corresponding to the first 90-degree phase shifter; the first 90-degree phase shifter and the first 90-degree reference microstrip line are respectively connected to four T-shaped power dividers; the third Wilkinson power divider is respectively connected to the second 90-degree phase shifter and the second 90-degree reference microstrip line corresponding to the second 90-degree phase shifter; the second 90-degree phase shifter and the second 90-degree reference microstrip line are respectively connected to four T-shaped power dividers.

2. The broadband circularly polarized metasurface antenna with reduced in-band and out-of-band radar cross-section as described in claim 1, characterized in that, The first dielectric substrate is an F4BM265 dielectric substrate with a thickness h1 = 3 mm.

3. The broadband circularly polarized metasurface antenna with reduced in-band and out-of-band radar cross-section as described in claim 2, characterized in that, The second dielectric substrate is an F4BM265 dielectric substrate with a thickness h3 = 0.1 mm.

4. The broadband circularly polarized metasurface antenna with reduced in-band and out-of-band radar cross-section as described in claim 3, characterized in that, The adhesive layer connecting the first dielectric substrate and the second dielectric substrate is an RO4450F prepreg with a thickness of h2 = 0.2 mm.

5. The broadband circularly polarized metasurface antenna with reduced in-band and out-of-band radar cross-section as described in claim 4, characterized in that, The thickness of the C-shaped metal patch, the round metal patch, and the L-shaped metal patch is 0.018mm, and all the metal materials are copper.

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