Coplanar waveguide wideband band-stop filter based on localized spoof surface plasmons

Abstract

In this work, a wideband band-stop plasmonic filter based on localized spoof surface plasmons is reported, which consists of a coplanar waveguide (CPW) and an ultra-thin periodic corrugated metallic strip with defect units at the back of the substrate. Defect units are used to localize the transmission energy along the CPW. Each defect unit can introduce a narrow stop band, and a series of defect units is judiciously designed to form a broadband CPW band-stop filter. The center frequency and bandwidth of the filter can be tuned by the heights and numbers of the defect units. In addition, a $T$-shaped unit is designed to increase the equivalent height of the lateral branch so as to realize the miniaturization of the vertical geometric dimension. Theoretical analysis of the filter has been conducted, and a sample at microwave frequency has been fabricated and measured to validate our design. This simple band-stop plasmonic filter can find potential applications in plasmonic circuits and antennas at microwave and terahertz frequencies.