Stretchable frequency selective surfaces for large-area-tuning and high-power applications

摘要

Frequency selective surfaces (FSSs) have been widely used in modern communications and military applications such as radomes and RCS reductions. In some circumstances, their filtering responses need to be tuned from one frequency band to another. For most tuning techniques, it's still a challenging problem for large-area FSSs. Take electronic tuning for example, it requires lots of electronic controllable elements and RF/DC isolations depending on the sizes of the FSS. In this research, we investigate a mechanical tuning approach of using stretching to tune the frequency response of a large-area FSS. Instead of exploiting a complicated bias circuit for individual unit cell, the responses can be shifted by increasing the mechanical loadings added on the edges of the entire frame of the FSS. The proposed FSS in this research was composed of two inductive horseshoe-shaped strips separated by a capacitive gap forming a first-order band-stop filter. The mechanical stretch and the induced tuning of a unit cell are studied separately by finite element method and full-wave EM simulations. A prototype was designed, fabricated, and examined with an X-band waveguide measurement. The research results are expected to be beneficial for high-power-microwave devices and mm-wave applications.