一种兼具宽带增益改善和宽带、宽角度低雷达散射截面的微带天线

设计并制备了一种兼具高增益和低雷达散射截面(radar cross section, RCS)的微带天线, 通过给原始微带天线加载双屏频率选择表面(frequency selective surface, FSS)覆层, 使其具有宽带的3 dB增益带宽和宽带、宽角度的低RCS特性. 该FSS单元的上层是四个开口处都焊有电阻的金属环结构, 下层是中间和四边都开缝的金属贴片结构. 上层加载的电阻主要用于吸收雷达入射波, 减缩天线RCS; 下层的贴片和天线地板构成Fabry-Perot谐振腔, 提高天线增益. 在5.75–11.37 GHz频带内, S₂₂<-10 dB, S₁₂<-10 dB; 在11.21–11.54 GHz频带内, S₁₁反射系数相位曲线斜率为正, 幅度模值均在0.86以上. 实验结果表明: 与原始天线相比, 在谐振频点11.73 GHz处, 天线增益提高3.4 dB, E, H面的半功率波束宽度分别减小16°和50°; 天线的3 dB增益带宽为10.00–12.40 GHz, 完全覆盖阻抗带宽. 在4.10–11.30 GHz 频带内, 天线法向RCS均有3 dB以上的减缩, 最大减缩23.08 dB; 4.95 GHz处的单站RCS在-20°–20°的角域、双站RCS 在-37°–37°的角域均有3 dB以上的减缩. 实验结果证实了该FSS覆层可用于同时改善天线的辐射和散射 性能. 关键词： 频率选择表面 低雷达散射截面 高增益 宽带

A broad-band gain improvement and wide-band,wide-angle low radar cross section microstrip antenna

A novel high-gain and low radar cross section (RCS) microstrip antenna is designed and fabricated. The proposed antenna obtained broad-band 3 dB gain bandwidth and wide-band, wide-angle low RCS properties after applying the frequency selective surface (FSS) as a superstrate of original microstrip antenna. The FSS cell is composed of two metallic layers separated by a dielectric substrate. A metallic square loop with four resistors mounted on each side of the loop is enched on the top layer and a metallic plane with a central cross slot and four fringe slots is enched on the bottom layer. The four resistors of top layer are mainly used to absorb radar incoming wave and reduce antenna RCS. The patch of bottom layer can constructe a Fabry-Perot resonance cavity with ground plane and improve the antenna gain. The reflection coefficient S₂₂ and transmission coefficient S₁₂ of top layer are all below -10 dB at 5.75-11.37 GHz. The reflection phase gradient of bottom layer is positive and the reflection magnitude value is above 0.86 from 11.21 GHz to 11.54 GHz. Measurement results show that the antenna gain is enhanced by about 3.4 dB at 11.73 GHz, and the half-power beam width of E-plane and H-plane is reduced 16° and 50° respectively. The 3 dB gain bandwidth is about 2.4 GHz which from 10.0 GHz to 12.4 GHz and well cover the impedance bandwidth. The proposed antenan achieved an RCS reduction of more than 3 dB in the normal direction at 4.10-11.30 GHz, the largest reduction reached 23.08 dB in comparison with the original antenna. The monostatic and bistatic RCS reduction are over 3 dB from -20° to 20° and -37° to 37° respectively at 4.95 GHz. The results proved the FSS superstrate can be applied to improve the radiation and scattering performance simultaneously.
Keywords： frequency selective surface low radar cross section high-gain wide-band