Planar microwave frequency splitter and coupler based on conformal surface plasmonic structures

Recently, a conformal surface plasmon (CSP) structure has been successfully proposed which is believed very promising for the design of plasmonic devices and circuits in the frequency range from microwave to mid-infrared. In this paper, we investigate the dispersion relation of a proposed symmetric CSP structure which shows that two types of guided modes can be supported by such symmetric CSP structure: the symmetric mode (even mode) and the anti-symmetric mode (odd mode). By utilizing the even guided mode, we have designed a CSP frequency splitter and a coupler based on the symmetric CSP structure in the microwave frequency range. The designed devices exhibit good performance that is validated through both electromagnetic simulation and the experimental test on fabricated prototypes.