Dual-Band Polarization-Independent Absorber Based on Resistive Frequency Selective Surface

Abstract

In this paper, a three-layered frequency-selective absorber (FSA) that can efficiently absorb electromagnetic waves (EM) in a double-band is proposed. The proposed structure is designed so that signals reflected from the frequency selective ground plane are located at 2.4 and 5.5 GHz (ISM and UNII bands) and absorbed by the front resistive layers. Simulation results show that the proposed absorber not only blocks transmission in the desired bands but absorbs the signals reflected from the conductive layer. Reflective FSS unit cells are composed of double square loops printed on an FR-4 substrate and the resistive layers are formed of OhmegaPly material with a resistivity of 50 ohms per square. Furthermore, the proposed absorber is 0.17λ thick at the lowest frequency of absorption. The experimental results agree with the numerical simulations and show an absorptivity of more than 90% at 2.4 and 5.5 GHz, covering entirely ISM and UNII bands.