Plasma reconfigurable metamaterial using a 6.5 GHz dielectric resonator array

Plasma formation between coupled dielectric resonators (DRs) is frequency scaled from 1 GHz to 7 GHz. Previous research found that applying low-power microwaves to a pair of calcium titanate (CaTiO₃) resonators could ignite plasma between them using the HEM₁₁₁ resonance mode. Those large, 1 GHz DRs are scaled down in size, and thus scaled up in frequency. The optimum relative permittivity of DRs for plasma formation is reported to be 200, confirming that CaTiO₃ (ɛ_r ∼170 ± 5) is a good material to use for plasma-forming DRs. This paper presents data collected for a 2D array of resonators operating in the 6-7 GHz range for separation distances of 0.25 mm and 0.5 mm in a 1-10 Torr argon gas environment. Gas breakdown data for two DR configurations are compared to the Raizer theory at 1.1 GHz and 6.5 GHz. Plasma modulation of the reflection and transmission of DR arrays with plasma on and off indicates possible future applications as a frequency selective filter.