Ultrawideband lightweight absorber based on composite strategy with active control of absorption in the UHF band

Abstract

In this paper, a composite strategy has been developed to achieve continuous absorption coverage from the ultrahigh-frequency (UHF) band to the Ku band. Based on this strategy, an ultrawideband lightweight composite metamaterial absorber is fabricated and measured. The composite absorber comprises two cascaded parts operating in separated frequency bands. First, we design a polarization-insensitive tunable absorber in the UHF band based on the equivalent circuit model. The measured results indicate that the tunable UHF absorber obtains a tunable −10 dB reflection coefficient from 0.88 to 1.48 GHz. Furthermore, a lightweight 3D absorber is applied to cascade with the tunable UHF absorber to constitute a ultrawideband composite absorber. The composite absorber achieves an ultrawideband absorption ranging from 0.78 to 18 GHz with a reflection coefficient below −10 dB. The overall composite structure is extremely lightweight with a surface density below 0.2897 g cm−2. This composite absorber also exhibits good angular stability, low profile, and polarization insensitiveness. We think this work is of great application potential for military and civilian applications.