Restrain the spurious resonance of second-order fractal frequency selective surface in MMW band

Abstract

Based on analyzing the equivalent circuit and electric field distribution of second-order square fractal frequency selective surface (FSS), the mechanism of its spurious resonance is discussed. To achieve a millimeter wave (MMW) spatial filter which exhibits high out-band suppression(≥13dB) and insensitive to the variation of oblique incident angles for both TE and TM polarized waves, a hybrid methodology of decoupling operation in conjunction with discrete particle swarm optimization (DPSO) procedure is proposed. The FSS array without spurious resonance and its evolutionary process by DPSO are described. It is also demonstrated that the measured results and DPSO-operated frequency characteristics are in excellent agreement.