A reconfigurable frequency selective structure using plasma arrays

In this paper, a novel structure composed of frequency selective surface and plasma arrays is proposed to control the propagation of the free space electromagnetic wave in the X band of the microwave spectrum. Plasma is hard to be used for controlling the propagation of microwave due to its electron density, electron temperature, spatial volume, and distribution continuity, which are too rigorous to be satisfied for most plasma generation methodologies. The idea of this paper lies in that the impedance characteristics of the plasmas could be effectively tuned by periodic structures so that the wave propagation tuning effects of plasmas could be activated under conditions of restricted dimensions of (0.27–0.41)λ0, where the plasma arrays are shown not to be effective alone. The system is described based on transmission line approximation, and the characteristic lumped units have been analyzed using experimental data fitting. It is argued that the properties and the methodology discussed in this paper could be applied in the design of artificial microwave media, especially in the field of active absorbing frequency selective surfaces.