基于宽带吸波体的微带天线雷达散射截面缩减设计

Radar cross section reduction of microstrip antenna based on wide-band metamaterial absorber

利用加载集总电阻的方式设计出一种极化稳定且宽入射角的宽带超材料吸波体(wide-band metamaterial absorber,WBMA),在平面波垂直入射时,其吸波半波功率带宽达12.7 GHz,吸波率大于90%的带宽达10.42 GHz,峰值吸波率达99.9%.将其与微带天线共基板共接地板的方式加载,制备出WBMA微带天线,实现了天线宽频域内雷达散射截面(radar cross section,RCS)大幅缩减.仿真与实测结果表明:将WBMA加载于微带天线后,天线的前向增益提高了0.53 d B,整体辐射特性基本保持不变;在不同极化波下,天线的工作频带带内和带外等宽频域(6.95—17.91 GHz)内的单站RCS缩减大于3 d B以上,最大缩减值达21.2 d B;在天线的中心频点8 GHz处±48°的宽角域内,双站RCS缩减效果明显,很好地实现了天线的宽频域大角度的隐身设计.

We design a wide-band metamaterial absorber （WBMA） with stable polarization and wide incident angle by loading a lumped resistance. The full-width at half-maximum of the absorber is 98%, the bandwidth of absorbing rate of more than 90% reaches 10.42 GHz, and the peak absorbing rate is 99.9% in the normal wave incidence. Loading the WBMA around the microstrip antenna by sharing the same substrate and ground plane, we fabricate the WBMA antenna, whose radar cross section （RCS） sharply decreases in the wide frequency range. Simulation and experimental results show that the antenna＇s radiation pattern is almost unchanged： just only the former gain improves 0.53 dB after loading the WBMA. Under different polarized waves, the antenna＇s monostatic RCS reduction is more than 3 dB within the working frequency band and beyond the working frequency band （6.95-17.91 GHz）, the maximum value is 21.2 dB. The bistatic RCS decreases significantly from -48° to 48°at the middle working frequency （8 GHz）, which well achieves the antenna stealth at the wide-band frequency and wide angle.