中文摘要：

设计了一种基于分形树结构的高性能频率选择表面（frequency selective surface,FSS）,并将其作为微带天线的空间滤波器,同时改善天线的辐射与散射性能.该FSS单元是由两层金属及其中间介质组成,上、下层金属采用金属柱连结,整体构成树枝状分形结构.通过优化参数,得到了一种宽带、极化无关、宽入射角、小型化的超薄FSS,厚度只有约0.017λ.将该FSS应用于微带天线后,天线的相对带宽拓展到40%,工作频段内的增益得到改善,9.6 GHz时,天线的增益提高了6.7 dB,同时,天线工作频带内的雷达散射截面（radar cross section,RCS）也得到了明显减缩,最大减缩为12.7 dB.实验结果与仿真结果符合得较好,证实了该空间滤波器具有提高宽带天线增益、增强天线定向性、改善天线带宽与降低天线带内RCS的效果,可以应用于宽带天线带内辐射与散射性能的同时改善.

英文摘要：

A novel frequency selective surface（FSS） with stable performance is designed and applied to microstrip antenna.The FSS cell is composed of two metallic layers separated by a dielectric spacer.The top and bottom layers connected with metallic cylinders form the fractal dendritic model.By optimizing the geometric parameters of the model,an ultrathin FSS spatial flter is obtained,whose thickness is only 0.017λ,with wideband,polarization insensitive,wide-incident angle,and miniaturization properties.When applying the radome to microstrip antenna,the bandwidth of the antenna is improved to 40%,the gain is enhanced in the whole operating frequency band,especially at 9.6 GHz,the gain is increased by 6.7 dB;at the same time,the in-band radar cross section（RCS） is reduced signifcantly,and the largest reduction exceeds 12.7 dB.Experimental results are in good agreement with the simulated ones,which verifes that the novel FSS spatial flter can be used to increase the gain of broadband antenna,enhance the directivity,improve the bandwidth,and reduce the in-band RCS;to sum up,it can be applied to broadband antennas to improve their radiation as well as scattering performance at one time.