3-D Band-Absorptive Frequency Selective Rasorber Based on Stepped-Impedance Hybrid Transmission/Absorption Channels

A 3-D band-absorptive frequency selective rasorber based on stepped-impedance hybrid transmission/absorption channels is proposed in this paper. These two channels act as a 3D absorber within its absorption band, while it is like two stacked parallel-plate waveguides (PPWs) below the absorption band. Therefore, the proposed FSR exhibits an absorption band from 3.78 GHz to 7.14 GHz, with a fractional bandwidth of 61.53%, and the cut-off frequency of the passband is 931MHz ( $\vert S_{21}\vert \geq-1\text{dB}$ ).