Dual‐polarization 3D FSR with a high selectivity and wide transmission passband

Abstract This letter, based on 3D slotline structures (SLSs), proposes a dual‐polarization frequency selective rasorber (FSR) with a high selectivity and wide transmission passband. The broadband transmission and absorption paths are created by etching three independent SLSs onto the 3D periodic printed circuit boards (PCBs). These include an open‐circuit slotline that is loaded with both a metal strip and an LC structure at its centre, as well as two short‐circuit slotlines that are loaded with lumped resistors. With this design, two transmission zeros (TZs) are introduced to achieve a fast transition between the passband and absorption bands. Through analysing surface currents and electric field distributions, the working principle is elucidated. The proposed FSR is designed, manufactured, and measured. Simulation and experimental results demonstrate that the presented FSR exhibits broadband characteristics, high selectivity, and angular stability.