Flexible Serpentine-like Frequency Selective Surface for Conformal Applications with Stable Frequency Response

In this letter, a flexible stopband frequency selective surface (FSS) with serpentine stripe unit cell is presented. Compared with the FSS with straight stripe and zigzag stripe unit cell, the proposed FSS on planar thin polyimide (PI) substrate shows very small offset of resonant frequency with electromagnetic waves having incident angles from 0 $^\circ$ to 60 $^\circ$ , according to the simulation results. The stable transmission performance of flexible FSS with serpentine stripe unit cell on PI substrate is further demonstrated by the computational and experimental results. When the FSS with serpentine stripe unit cell is bent with bending angles from $ \pi /3$ to $ \pi$ , the offset of resonant frequency is negligible, whereas the resonant frequency of FSS with straight stripe and zigzag stripe unit cell shifts about 15.4% and 5.8% when bending angle is $ \pi$ , respectively.