Active frequency selective surface with tunable and switchable properties based on loaded split ring slots

Abstract

An active frequency selective surface (AFSS) with reconfigurable tunable and switchable properties is studied in this Letter. The AFSS unit cell consists of a split ring slot resonator loaded with a varactor diode. The proper biasing of the varactor diode enables diverse functional modes. The proposed AFSS with a single control device in each unit cell demonstrates transmitting and reflecting properties in two operating bands. Additionally, in one of the bands, the tuning of the resonant frequency is achieved in a transmission window. A unit cell active diaphragm at X-band has been designed and fabricated to characterise the AFSS based on the waveguide simulator. The measured results, using the waveguide simulator approach, show either a transmitting tunable or reflecting response in the lower band with resonant frequencies from 9.002 to 9.354 GHz and a transmitting or reflecting response in the upper band at the centre frequency of 11.87 GHz.