Frequency splitter based on spoof surface plasmon polariton transmission lines

Abstract

We propose a frequency splitter based on spoof surface plasmon polariton (SSPP) transmission lines (TLs). The device consists of two bent domino SSPP TLs with different geometric parameters, leading to different passbands, forming two frequency band branches. A transition from a rectangular waveguide to the two SSPP TLs is designed for frequency splitting. To achieve efficient transition for both branches in their respective frequency bands, different transition lengths of the two branches and a shifted placement from the center are adopted. Furthermore, for the high frequency band branch, to obtain satisfactory out-of-band rejection below the lower cut-off frequency, an SSPP bandstop structure is introduced by placing SSPP TL sections along the main SSPP TL. A prototype is designed, fabricated, and evaluated. The results prove the feasibility of the proposed SSPP frequency splitter.