Characteristic Mode Analysis of Complex Spoof Localized Surface Plasmon Resonators

In this paper, characteristic mode analysis (CMA) is originally applied to investigate complex spoof localized surface plasmon (LSP) resonators, including a traditional toroid spoof-LSP resonator, and three Fabry-Perot type spoof-LSP resonators with different boundary conditions: open, shorted, and reactive. Compared with three traditional analytical methods of spoof LSP: dispersion curve approximation, near-field measurement (NFM), and extinction cross-sectional simulation (ECSS), CMA has three main advantages: to provide an insight of intrinsic resonances independent of excitations, to provide eigencurrents distribution, and to track each resonant mode at the full frequency band even when many resonant modes coexist at a very narrow band. Resonant frequencies calculated by CMA match well with that obtained by NFM and ECSS, indicating the correctness of CMA method. Based on CMA, bandwidths and eigencurrents of different resonant modes are also presented. It is foreseeable that CMA could be further utilized in spoof-LSP designs for various applications.