Abstract

This letter introduces a novel compact Spoof Surface Plasmon Polaritons (SSPPs) based low-pass filter (LPF) with ultra-wide out-of-band suppression. The filter design employs a single-layer printed circuit board, with the top layer incorporating metal gratings in a tilted slotted stub shape. The unique characteristic of the proposed SSPP LPF is the lower asymptotic frequency compared to traditional SSPP structures of equivalent size, making significant LPF miniaturization. The overall device size is 0.75λg × 0.12λg (where λg denotes the guided wavelength). A lumped equivalent circuit model of the proposed SSPP unit cell is presented. Simulated results showcase excellent performance in the passband and impressive out-ofband suppression. A prototype of the proposed LPF is fabricated and measured to validate the design concept. Measured results closely align with simulation outcomes, revealing an insertion loss of 1.1 dB at the center frequency, reflection coefficient below-10 dB throughout the pass-band, and exceptional out-of-band rejection with an attenuation exceeding 30 dB for over 38 GHz.