Novel crest‐trough shaped spoof surface plasmon polaritons for low pass filtering applications

Abstract

In this letter, a novel periodic crest‐trough (CT) shaped groove structure is proposed to excite and propagate spoof surface plasmon polaritons (SSPPs) at microwave frequency. Such a groove shape solves the problem of high transmission losses found in traditional microstrip transmission lines and presents tighter field confinement. Lower dispersion band is achieved by proposed CT‐SSPPs as compared to traditional structures, with 28% reduced asymptotic frequency than rectangular groove. Influence of some geometrical parameters is also explored. Further, planar low‐pass plasmonic filters with low reflection and high efficiency are investigated with compact transition circuitry for smooth and fast conversion between SSPPs and guided waves. To validate the proposed performance, two plasmonic filter structures are fabricated and measured. Full agreement is observed between the simulated and measured results for which reflection coefficient is lower than −10 dB in passband up to 3.07 and 2.52 GHz, respectively for both filters. The rejection level is higher than −15 dB in the whole stopband.

Spoof surface plasmonics: principle, design, and applications

“…SSPPs show good high-frequency suppression characteristics during transmission, which provide the feasibility to design low-pass filters. Based on this principle, several effective low-pass filters have been proposed combined with CPW or microstrip line to construct TEM (transverse electronmagnetic)-SSPP hybrid mode [33][34][35][36][37], which provides a design basis for more advanced plasma functions and integrated circuit work in the future. Due to the high frequency suppression of SSPPs, the transmission zeros can be simply introduced in the low frequencies when designing the bandpass filter, which can embody their unique advantages.…”