An Ultra-Wideband Absorber Based on Mixed Absorption Mechanisms

In this communication, an ultra-wideband (UWB) absorber is proposed by the employment of two absorption mechanisms, including resonance-base absorber and spoof surface plasmon polariton (SSPP) absorber. The mixed absorber is a 3-D structure which consists of a vertically placed SSPP and resonance-based absorber and a horizontally placed resistive frequency selective surface (FSS). The UWB absorption performance mainly originates from the absorption characteristic of the resonance-based structure in the low-frequency range and the SSPP structure in the high-frequency range. Simulation shows that the hybrid structure possesses a −10-dB fractional bandwidth (FBW) of 160.7% from 1.45 to 13.33 GHz with the thickness of 20.6 mm (
$0.1\lambda _{L}$
,
$\lambda _{L}$
is the wavelength at the lowest frequency in free space of the absorption band) under both TE and TM polarizations. A prototype is fabricated and measured. The experimental results are in good agreement with the simulation results. The present work provides a new strategy to design UWB absorbers in a way that does not introduce extra thickness.