Investigation on the broadband active filtering characteristics of plasma composited frequency selective surface structure.

To address the demand for wideband, dynamically controllable filtering characteristics in radomes, a plasma composited frequency selective surface (PC-FSS) structure with broadband, active filtering properties is proposed and experimentally demonstrated. Initially, a broadband band-pass FSS was designed using a multilayer cascade method and integrated with inductively coupled plasma (ICP) to form the PC-FSS. The effects of various discharge conditions-including pressure, power, and ICP thickness-on the parameter distribution and filtering performance of the PC-FSS were investigated through experimental measurements. The results indicate that the filtering characteristics of the PC-FSS can be actively controlled across a wide frequency range by adjusting the discharge conditions. Furthermore, the PC-FSS exhibits strong polarization and angular stability. In its unexcited state, the PC-FSS functions as a broadband band-pass structure with a center frequency of 13.56 GHz and a -1 dB passband of 11.02 GHz (ranging from 8.05 to 19.07 GHz). When excited, the structure displays tunable band-pass and band-stop characteristics, which depend on the discharge conditions, thereby providing both switching and tuning functionalities. The active properties of the PC-FSS underscore its potential for applications in active stealth radome systems.