A Low-Frequency Frequency Selective Absorber based on Crenel Structure

This paper proposes a crenel frequency selective surface (FSS) for low-frequency electromagnetic wave absorption. To further expand the absorption bandwidth into the P-band range (0.3-1.0GHz), a three-dimensional (3D) folding of the upper patch is performed on a double-layer square patch structure. Two types of FSS structures made of loss resistance sheets are etched on thin polyethylene terephthalate films. The equivalent circuit method is used to model the FSS structures, and the basic principle of low-frequency absorption in the crenel structure was analyzed. In optimizing the function of the FSS structure, the influence of folding angle on low-frequency electromagnetic wave absorption is mainly analyzed. The results of the crenel structure and unfolding structure absorber in two polarization states are compared, and the optimization results are given. The proposed absorber can operate in the frequency bands of 0.44-2.78 GHz and 0.42-2.89 GHz under transverse electric and magnetic polarizations, respectively, with absorption rates exceeding 90%.