Low-Profile Second-Order Terahertz Bandpass Frequency Selective Surface with Sharp Transitions

This paper proposes a new approach to implement Frequency Selective Surfaces (FSSs) with sharp transition edges and almost flat bandpass responses. The design is suitable for submillimetre wave and terahertz applications. The proposed structure exhibits a low insertion loss in the desired band. The structure is realized by combining bandstop and bandpass FSS structures on the same plane. By cascading more than one layers of surfaces, separated by dielectric slabs, the response with the desired flat passband characteristics can be achieved. The structure is polarization independent and exhibits low insertion loss at the passband around 170 GHz.