<i>W</i>-Band Bandpass Filter Using Spoof Surface Plasmon Polaritons and Double-Grating Rectangular Waveguide
Qinlong Li, Guo Da-peng, Jianxing Li, Kai‐Da Xu
Abstract
A hybrid circuit with spoof surface plasmon polaritons (SSPPs) and double-grating rectangular waveguide (DG-RWG) is proposed to design a bandpass filter (BPF) operating at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${W}$ </tex-math></inline-formula> -band. The proposed SSPPs consisting of corrugated metallic blocks are embedded into the RWG, which forms a hybrid SSPP-RWG. Both the dispersion curves of the SSPP-RWG and DG-RWG are analyzed. The lower cut-off frequency of DG-RWG and the upper cut-off frequency of SSPP-RWG can be controlled independently by changing their geometric parameters, thus the hybrid circuit composed of DG-RWG and SSPP-RWG is attractive to design a BPF with tunable bandwidth. For demonstration, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${W}$ </tex-math></inline-formula> -band RWG BPF is designed and fabricated with measured bandwidth from 80.1 to 93.8 GHz, which agrees well with that in the dispersion curves. The BPF has a low insertion loss of about 0.57 dB at the center frequency.