Ultra-thin wideband absorbers comprised of pixelized Frequency Selective Surfaces

An ultra-thin wideband absorber is proposed comprised of two cascaded layers. The first layer is a pixelized Frequency Selective Surface (FSS) engineered to exhibit the response of a series RLC circuit. The FSS is placed at a small but useful distance above a mushroom-type artificial magnetic conductor (AMC). The admittances of the two structures cancel each other resulting in an almost zero input reactance within the frequency range of interest. A -10dB return loss is achieved for normal incidence from 9-13 GHz, while the total thickness of the structure does not exceed 2 mm.