用最小结构单元频率选择表面实现大入射角宽频带的透波材料

Wideband and large incident angle wave transparent material based on frequency selective surface with miniaturized elements

不同于传统的频率选择表面(FSS),最小单元频率选择表面(mFSS)的工作频率取决于其基本结构单元中金属结构的内禀电容和电感,而不是单元的结构共振频率.本文围绕用mFSS构建带通型透波材料,在分析了金属缝隙和金属线的内禀电容和电感的基础上,构建了以金属缝隙和金属线为基本单元的透波材料模型,研究了mFSS单元结构参数、等效电路参数和电波入射角对透波性能和带宽的影响,设计制备了工作在10 GHz的透波材料.研究结果表明;这种透波材料具有工作频带宽,对电磁波入射角度和极化方向不敏感等优点,在垂直入射时的-1 dB带宽达到40%,即使在大入射角(60?)下依然有很好的传输性能,-1 dB带宽接近20%.实际制备的透波材料样品的测试结果和与理论计算结果相一致.mFSS的上述特性极大扩展了透波材料的应用场合,特别适用于雷达罩和天线罩等应用.

Different from the traditional frequency selective surface, the working frequency of a frequency selective surface with miniaturized elements （mFSS） is based on the intrinsic capacitance and inductance of its unit cell, but not the structure resonance. Focusing on the application of mFSS in wave transparent material （WTM）, we have designed a band-pass WTM with unit cell of metal patch and wire, analyzed their intrinsic capacitance and inductance, and explored the parameters of the mFSS unit and its equivalent circuit on the performances of WTM. A bandpass WTM sample working at 10 GHz is designed and fabricated. Measurements demonstrate that the sample is wideband, insensitive to the incident angle, and polarization independent;the-1 dB bandwidth is over 40%at normal incidence and up to 20%even at large incident angles 60°. Experimental results are in good agreements with the calculations. The advantages of mFSS based WTM can expand its applications in microwave engineering, especially the radomes.