Nano-plasma tunable evanescent-mode cavity resonators

Conventional tunning mechanisms for evanescent-mode cavity resonators include changing a gap size through MEMS-based structures. In this paper, for the first time, we propose a technique for adjusting the resonant frequency of these resonators by using a nano-plasma region. For this aim, a sufficiently large DC field is applied which generates a nano-plasma layer inside the gap between the loading post and the top wall of the cavity. The thickness as well as the electromagnetic characteristics of this plasma layer and consequently the capacitance of the resonator are controlled by varying the applied DC field. This technique is potentially simpler than mechanically changing the gap size. As a proof of principle, we consider a 50 GHz resonator whose resonant frequency decreases down to 34.6 GHz when the applied DC voltage goes up to 94 V.