Wide-Bandpass Filtering Due to Multipole Resonances of Spoof Localized Surface Plasmons

Wide-bandpass filters are proposed based on multipole resonances of spoof localized surface plasmons (SLSPs). The resonance characteristics and geometric tunability of SLSPs are investigated under simulations and equivalent circuit modeling. Strong coupling with interlayer microstrip lines is proposed to join discrete multipole resonances into a continuous and flat passband. The SLSP filters exhibit wide-passband features in compact sizes and well-balanced shapes, while holding satisfactory suppression of spurious passband, group delays, and geometric tunability. This work exposes the SLSP application potential in filters as novel resonators.