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.