Wideband 3D Frequency Selective Rasorber with Two Absorption Bands

This paper presents a 3D frequency selective rasorber consisting of 2D periodic array of open-circuited and short-circuited parallel-plate waveguides. The passband is obtained by the lossless open-circuited parallel-plate waveguide, while two absorption bands located at both sides of the passband are produced by the lossy short-circuited parallel-plate waveguide loaded with a chip resistor. A capacitor is inserted in the short-circuited parallel-plate waveguide, creating an additional resonator, which greatly expands the upper absorption bandwidth. The geometrical details of the proposed FSR are depicted, and simulated performances as well as some analysis are given.