即贴型单层带通FSS的传输特性

Transmission properties of adhesive single-layer bandpass FSS

以狭缝阵列为例,利用模匹配法并结合实验对即贴型频率选择表面(FSS)与介质板的复合结构进行了研究,分析了不同厚度的聚酰亚胺基底膜和粘合胶层对谐振频率的影响以及不同复合方式下的频率响应。结果表明,即贴型FSS结构中,基底膜与粘合胶层等细节的影响不可忽略,影响程度与复合方式和介质厚度均密切相关。复合结构中应当含有粘合胶层,避免空气间隙的影响。仅当基底膜和粘合胶层的介电常数小于介质板或与之相近,且介质板厚度为基底膜和粘合胶层厚度的10倍以上时,采用合适的复合方式,才能使基底膜和粘合胶层对复合结构传输特性的影响降至最低。一系列厚度的介质单侧加载时的FSS结构频率响应测试结果与计算结果的对比表明,粘合工艺的缺陷会导致即贴型FSS结构的传输性能发生变化,FSS的设计应当全面考虑上述因素的影响。

By taking slot arrays as illustrative examples, the compound structures of Frequency-Selec- tive-Surface （FSS） and dielectric slab were investigated based on modal matching method and experimentation. The frequency responses of FSS structures by different compounding approaches were analyzed, including the influence of polyimide base film and adhesive coating with different thicknesses on resonant frequency. The results show that the influence of base film and adhesive coating in FSS structures can not be neglected, for they have a close relationship with the compounding approach and dielectric thickness. The compound structure should contain adhesive coating to eliminate the effect of air gap. When dielectric constants of base film and adhesive coating are less than or close to that of the slab only, the slab is over 10 times thicker than those of base film and adhesive coating, the influence of base film and adhesive coating on the transmission properties of properly compound structures would be the minimum. The comparison of measurement and computation of frequency response of FSS structures loaded with dielectric slab of a series thickness on one side shows that the flaw of adhesion will change the transmission properties of FSS structures. All factors mentioned above should be considered in FSS design.