Angularly Stable Frequency-Selective Surface Using Shifted Double-Sided Screens

In this letter, a shifted double-sided frequency selective surface (FSS) with miniaturized unit cells is proposed to achieve superior performance in angular insensitivity. Two identical FSS screens mounted on both sides of a thin substrate have lateral displacement relative to each other. We shed light into effect of shifting by investigating current and field distributions, and present the operating principles of the proposed FSS along with the equivalent circuit model. The whole structure has a lower profile (a thickness of 0.001λ, where λ represents the resonant wavelength in free space) as well as a small size (0.043λ × 0.043λ). This FSS as a bandpass spatial filter is stable with respect to different polarizations, polarized angles, and incident angles of the illuminating waves. A prototype of the proposed FSS is fabricated and tested. The measured frequency responses agree well with the simulated results.