High-Selectivity Frequency Selective Rasorber With Tunable Absorptivity

This paper 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 PIN diodes employed to achieve tunable absorptivity, and a high-quality (Q)-factor bandpass frequency-selective-surface (FSS) in the bottom, with 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 GHz 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.