High-Performance and Ultra-Broadband Metamaterial Absorber Based on Mixed Absorption Mechanisms

Abstract

Perfect absorbers are highly desirable in many military applications, such as radar cross section (RCS) reduction, cloaking devices, and also sensor detectors; however, most approaches (such as wedge and pyramidal absorbers, multi-resonant absorbers) intrinsically suffer from very large size at low-frequency domain, limited bandwidth, as well as low absorption ratio issues. In this paper, we solve these issues via combining the Huygens metasurface and three-layers slab impedance metasurface, with the former satisfying the novel impedance matching theory and the latter exhibiting multi-resonant property and optimized conductivities, which achieve high-efficiency absorption at lower frequency range (1-3 GHz) and higher frequency region (3-18 GHz), respectively. To demonstrate our concept, we design/fabricate a realistic metasurface absorber working in the microwave region, and perform experiments to demonstrate that it can achieve an ultra-broadband (1-18 GHz) performance with absorption rate better than 75%. The numerical simulations are in good agreements with experiments, indicating that the absorption efficiency can be further pushed to 92% within the whole working band by optimizing our designs. More importantly, our device is insensitive for different polarizations and oblique incidences. Our findings can stimulate the realizations of ultra-broadband meta-devices, particularly can enhance the cloaking technology relying on high-efficiency absorption.