Broadband transition between microstrip line and spoof SP waveguide

A broadband transition from microstrip line to spoof surface plasmon (SP) waveguide is proposed. The transition transforms the guided wave into a spoof SP polariton in a broad microwave frequency band. A back-to-back transition sample is fabricated using the proposed method. Good agreement between the measurement and simulation is obtained. The measured results show an insertion loss <2 dB and a return loss below -11 dB from 2.2 to 10 GHz. The proposed broadband transition may pave a way for advanced conventional plasmonic integrated microwave devices and circuits.