Dispersion-Engineered, Broadband, Wide-Angle, Polarization-Independent Microwave Metamaterial Absorber

In this article, by deliberately controlling multiple resistive electric and magnetic resonances in terms of dispersion and dissipation, a low-profile, wideband, microwave metamaterial absorber with wide-angle and polarization-independent responses is proposed. The proposed absorber comprises a planar array with resistance-loaded metallic cross patterns, and a vertical periodic crossed mesh array with resistance-loaded metallic ring patterns. The vertical periodic crossed mesh array was inserted between the planar array and the metal ground to improve the wide-angle polarization-independent absorption. The involved dispersion-engineered design strategy for angular- and polarization-insensitive responses is described with numerical evidences and electromagnetic response behaviors. A proof-of-concept absorber was fabricated and measured for verification. At quasi-normal incidence, the measured bandwidth characterized by more than 90% absorption was 2.11-3.89 GHz, i.e., a fractional bandwidth (FBW) of 59.3%. At the incident angle of 50°, the FBW of the absorption larger than 90% was 48.6%. The absorber was thin with a thickness of 13 mm, corresponding to 0.09λ
₀
at the lowest operating frequency. The numerical and experimental results demonstrated that our proposed strategy provides an effective way to achieve wide-angle and polarization-independent responses in a broadband; these responses are very promising for most strategic applications.