An adaptive plasma split-ring resonator: multiphysics simulation and experimental validation

This work presents a bi-phase plasma-loaded split ring resonator (SRR) that integrates the resonant characteristics of SRRs with the nonlinear, power-dependent dielectric behavior of plasma to realize a compact filter-limiter for high-power microwave (HPM) protection. A key novelty of this study is the development of a self-consistent multiphysics simulation framework in COMSOL that couples the RF and Plasma modules to simultaneously model gas breakdown, the time-dependent evolution of plasma parameters, and their feedback on the electromagnetic response of the device. This predictive approach surpasses traditional methods that assume static plasma properties or rely solely on Drude based approximations. An S-band prototype is fabricated to validate the model, demonstrating a 3-dB bandwidth (BW) of 1.6%, insertion loss (IL) of 1.45 dB, and over 40 dB of isolation, with strong agreement between simulation and measurement. The results showcase the potential of plasma enabled resonators and highlight the importance of multiphysics modeling in the design of next generation adaptive RF protection systems.