A Switchable Frequency Selective Rasorber With Wide Passband

Abstract

Frequency selective rasorbers with wide passband have been investigated for the stealth of wideband antennas over the past few years. However, the wide passband degrades its in-band stealth performance. Therefore, in this work, a switchable wide-passband rasorber, whose passband can be switched into absorption band, is proposed utilizing a frequency-selective surface (FSS) and two resistive layers. First, a switchable second-order FSS is presented and the design of switchable resistive layer with wide passband is analyzed. Second, the reactance variation of the low- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Q$</tex-math></inline-formula> resonator in switchable resistive layer during the switching process is investigated to elaborate its effects on the out-of-band absorption performance of rasorber. Third, a nonswitchable resistive layer is designed to improve out-of-band absorption. Simulated results indicate that in rasorbing state the proposed single-polarized device exhibits a passband from 3.5 to 4.8 GHz (31%) with insertion loss less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 1 dB and a low-reflection band from 0.93 to 7.16 GHz (154%). In absorbing state, the passband is eliminated and the device exhibits a wide low-reflection band from 0.96 to 6.85 GHz (150.8%).