High-Selectivity Frequency-Selective Rasorber With Tunable Absorptivity

This article presents a high-selectivity frequency-selective rasorber (FSR) with an adjustable out-band absorptivity property. This rasorber is composed of a dynamic absorptive frequency-selective surface (AFSS) on the top, with p-i-n diodes employed to achieve tunable absorptivity, and a high-quality ( $Q$ )-factor bandpass FSS in the bottom, with an aperture-coupled resonators (ACRs) structure to obtain a high-selectivity transparent window. To begin with, theoretical analyses and extensive simulations are performed to evaluate the performance. Subsequently, a prototype is fabricated and measured, showing a 1 dB transmission window with high selectivity at 8.43–8.51 GHz and electrical tuning on the absorption rate response with a wide tunable span of 0.9 at out bands of 4.43–7.76 and 9.21–13.45 GHz, respectively. The proposed rasorber with dynamic tunability of absorptivity can provide radar cross Section (RCS) consistent with the environment, which is potential for radar stealth, deception, and anti-identification.