Design of a Compact Single-Layer Frequency Selective Surface With High Oblique Stability

In this article, a compact single layer band stop frequency selective surface (FSS) with superior resonant stability is presented. The proposed FSS unit comprises of a symmetrically modified square loop. The square loop has been modified in order to increase the perimeter. Moreover, modified square loop is arranged in C4 rotational symmetry to ensure the polarization independence. The designed FSS exhibits highly stable response for the incident angle variation from 0° to 86°. At the resonant frequency of 5.54 GHz, its miniaturized unit cell size is 0.09 λ₀ × 0.09 λ₀ and the thickness is only 0.007 λ₀ . The operating phenomenon of this FSS is explicated by analyzing the equivalent circuit model, electric field and surface current distributions at resonant frequency. A test sample of the designed FSS has been constructed for the validation purpose. The transmission coefficients response of the proposed FSS has been measured and found to be congruent with the simulated responses. The salient features that distinguish the proposed FSS design over others are low complexity, low thickness, compact unit cell and excellent angular stability.