A Compact and High-Power Frequency-Selective Plasma Limiter with an Ultra-High Isolation

A novel frequency-selective limiter is introduced in this paper, which is based on integrating a plasma cell into an absorptive resonant topology. The limiter response transitions from all-pass to bandstop when the input power exceeds the threshold for gas breakdown inside the plasma cell. This is a consequence of the change from constructive interference in the all-pass mode to destructive interference in the bandstop mode due to the change in dielectric properties of the plasma cell. Implemented using two quarter-wave microstrip resonators, a gas discharge tube (GDT) as a plasma cell, and a delay line, a less than 1.6 dB loss, over 60 dB selective isolation with a measured FBW of 2.8% were achieved. This is despite the low-quality-factor resonators used in this prototype device and the intrinsic plasma loss. The limiter handles significantly high input power of over 100 W, better than the state-of-the-art frequency-selective limiters.