Waveguide Filter Using Frequency Selective Surface with Miniaturized Element

In this paper, a waveguide filter using miniaturized-element frequency selective surface (FSS) is presented. The proposed FSS is composed of periodic array of metallic patches separated by small gaps and metallic lines. The array of patches constitutes a capacitive surface and the lines a coupled inductive surface, which together act as a resonant structure. At about 5.0 GHz, a narrow bandpass response is designed. Dimensions of the FSS element are much smaller than the operating wavelength, which is less than 1/13λ. For this miniaturized element, grating lobes are restrained and do not appear event to 25 GHz. Moreover, the FSS has stable performances for various incident angles. Design procedure and measurement results of the FSS are presented and discussed.