Design of frequency selective absorber based on parallel LC resonators

Abstract

This paper describes a method of designing Frequency Selective Absorber (FSA) which has a transmission band between two neighboring absorption bands. The proposed FSA is composed of a lossy layer on the top and a lossless layer at the bottom. The transmission characteristic is produced by the parallel LC resonators embedded in the lossy layer while the absorption ability is realized by the lumped resistors constructed in the lossy layer. An equivalent circuit model (ECM) is developed and discussed for a better understanding of this method. An FSA prototype is fabricated and measured for demonstration. Experiments show that the proposed FSA has a transmission band at the center frequency of 8.14GHz, which agrees well with simulation. Both transmission and refection coefficients from 4.5GHz to 7.5GHz and from 9.1GHz to 11.3GHz are under −10 dB, which indicate good absorption in these frequency bands. In addition, the performance of the proposed FSA demonstrates a low sensitivity with respect to the polarization of incident EM waves and is maintained well when the incident angles range from 0° to 45°.