低频带通与带阻自由切换的频率选择表面

A frequency-selective surface structure arbitrarily switched between band-pass and band-stop responses at low frequency

为了在不同时域下获得兼具带通与带阻空间滤波功能的低频频率选择表面(FSS),提出了一种带通与带阻型FSS可自由切换的设计方法,即在基于卷曲技术设计的小型化FSS表面上贴装电控PIN二极管,并利用"场-路"协同仿真的方法进行建模与计算。其中,卷曲图案既是滤波结构,也是馈电导线。当PIN二极管导通时,卷曲图案缝隙处产生的电容C1与金属贴片电感L1构成并联LC回路,FSS表现为带通滤波功能;反之,焊盘处缝隙及反偏PIN二极管产生的电容C2与金属贴片电感L2串联,FSS切换为带阻滤波功能。采用印刷线路板及表面贴装工艺制作出了400 mm×400mm试验样件并采用自由空间法进行测试,仿真与测试结果表明:在2.45GHz处,当PIN二极管导通时,FSS表现为强透射性能,反之则表现出强反射效果。这种基于电控PIN二极管开关所实现的带通与带阻型FSS自由切换方法在通信、电磁屏蔽及雷达隐身等领域具有广阔的应用前景。

To obtain a frequency-selective surface（FSS）structure with band-pass and band-stop spatial filtering functions at low frequency in different time domains,a design method for switching between band-pass and band-stop responses of the FSS was proposed.It was consisted of mounting PIN diodes on the miniaturized FSS,which was designed based on a convolution technique,and utilizing EM/Circuit Co-Simulation for calculations and analysis.It was noteworthy that the convoluted pattern was not only the filtering structure,but also serves as the feeder.When PIN diodes were in the ON-state,the parallel LC circuit constituted by the inductance L1 of the metallicpatches and the capacitance C1 of the pattern slots represents the band-pass performance of the FSS.Conversely,the total capacitance C2 of the reversed PIN diodes and the gap between the pads in series with the inductance L2 of the metallic patches indicate the occurrence of band-stop performance for the FSS when the PIN diodes are in the OFF-state.Using aprinted circuit board and surface mounting technology,aprototype of 400 mm×400 mm was fabricated and measured by the free space method.The simulation and test results indicate that,for a frequency of 2.45 GHz,the FSS exhibits strong transmission when the PIN diodes are in the ON-state,whereas a strong reflection is obtained when the PIN diodes are in the OFF-state.With this method,arbitrary switching of the FSS between bandpass and band-stop responses is realized,based on electrically controlled PIN diodes,which has a broad range of prospective applications in the fields of telecommunication,electromagnetic shielding,and radar stealth.