Reconfigurable bandpass filter using Spoof Surface Plasmon Polaritons

Traditional microwave bandpass filters depend on lumped or distributed circuit elements, often resulting in complex designs with limited reconfigurability. These conventional methods fail to achieve both compactness and high efficiency while maintaining low transmission loss. In this project, we propose a reconfigurable bandpass filter utilizing Spoof Surface Plasmon Polaritons (SSPPs), which overcome these limitations by confining electromagnetic waves tightly and minimizing losses. Previous studies have focused on passive SSPP structures without addressing dynamic frequency tuning, limiting their practical applications. We introduce a coplanar waveguide with ground (CPWG) structure integrated with varactor diodes on an interdigital configuration, enabling tunability across a broad frequency range. Unlike traditional designs, this approach provides better integration capability, reduced footprint, and enhanced selectivity. The proposed filter operates within 8 GHz to 13 GHz, achieving S11 < −10 dB and S21 = −0.2 dB, making it a promising candidate for next-generation communication systems requiring compact and reconfigurable filtering solution

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