Widely tunable high-Q filter using plasma material

This paper presents a novel concept to tune the resonant frequency of an evanescent-mode substrate integrated waveguide resonator while maintaining a high-Q in the tuned frequency range. The tunability is based on the insertion of vertical switchable capacitive post within SIW cavity. The filter is tuned from 18 GHz to 7.5 GHz, with insertion losses ranging from 0.8 dB to 2 dB in the frequency range for 1.4% bandwidth filter. The main interest of this work is the use of argon material under high pressure and DC voltage to generate a dense plasma media.