一种编码式低雷达散射截面超表面天线阵列设计

A coding metasurface antenna array with low radar cross section

设计了一种非周期排布的低雷达散射截面超表面天线阵列.该阵列由两种天线单元构成,两种天线单元的上层贴片形状相同,正交放置,作为天线单元能以同种极化方式在相同频带下工作,作为超表面单元相互之间能形成180°±37°的有效相位差.阵列在x极化方向与y极化方向上分别利用相位对消与吸波原理减缩雷达散射截面.同时,根据编码超材料理论,使用编程软件将两种单元进行非周期编码,使阵列的反射场呈漫散射状分布,有效降低了其峰值雷达散射截面.仿真结果显示天线阵列的辐射性能良好.与同等大小的金属板相比,在x极化波垂直入射时,设计天线阵列单站雷达散射截面(radar cross section,RCS)的6 dB减缩带宽为4.8—7.4 GHz,相对带宽为42.6%;在y极化波垂直入射时,设计天线阵列单站RCS的6 dB减缩带宽为4.6—7.8 GHz,相对带宽为51.6%.同时,设计天线阵较棋盘式天线阵散射能量分布更加均匀,空间中RCS峰值明显降低.实测结果与仿真结果符合较好.

An aperiodic metasurface antenna array with low radar cross section(RCS)is designed.The upper patches of the two antenna elements have the same shape and are placed at an orthogonal position,which can effectively reduce the workload of simulating the reflection characteristics of the patch.As antenna elements,they have identical operational band and polarization mode,and as metasurfaces,they can form an effective phase difference of 180°±37°.The RCS of the array is reduced mainly by phase cancellation under the x polarization and by absorption under the y polarization.According to the coding metamaterial theory,the two elements can be coded aperiodically by using the programming software.Regarding element A and element B as“0”and“1”,respectively,the coding matrix can be solved by a genetic algorithm.Element A and element B are arranged according to positions“0”and“1”to obtain a proposed array.The scattering field of proposed array is diffusive,and the peak RCS is effectively reduced.In order to highlight the characteristics of the proposed array,the chessboard-type array is designed for comparison.The simulation results show that the radiation performance of proposed array is good.Comparing with the metal board of the same size,the 6 dB reduction bandwidth of the monostatic RCS is 4.8-7.4 GHz(relative bandwidth is 42.6%)under the x polarization and 4.6-7.8 GHz(relative bandwidth is 51.6%)under the y polarization.Comparing with the chessboard type array,the scattering energy distribution of the designed antenna array is very uniform and the peak RCS in space reduces obviously.When a 4.8 GHz electromagnetic wave is incident with different incident angles and polarization modes,the scattering field is diffusive.Compared with other similar arrays,the proposed array has advantages of simple design process and even scattering field.The experimental results are in good agreement with the simulation results.This work makes full use of the scattering characteristics of the antenna element itself to solve the problem that the array antenna possesses both good radiation characteristics and low scattering characteristics at the same time,and improves the design process of the antenna patch.This design method has certain universality and reference significance for designing the low RCS antenna array.