Angularly Stable Frequency Selective Surface Combined With a Wide-Scan Phased Array

A five-layer frequency selective surface (FSS) composed of subwavelength elements with large harmonic rejection bandwidth is presented. The FSS design is based on an equivalent circuit model, where the interlayer interaction is only described with a single transmission line representing the fundamental Floquet wave. A prototype of the designed FSS is fabricated, and the measured response exhibits good stability over a wide conical incidence range up to 45°. The FSS is combined with a wide-scanning connected array of dipoles to implement a phased array with integrated filtering properties. A dispersion analysis is performed to define the distance between the array and the FSS that avoids the propagation of surface waves between the combined structures, allowing to maximize the radiation efficiency. The performance of the array combined with the FSS is experimentally characterized, showing high-order harmonic rejection better than 17 dB over a large bandwidth.