Design of Ultra-Broadband Metamaterial Absorber with Ultra-Wide-Angle and Polarization Stability

We investigate the underlying mechanisms of impedance mismatch under oblique incidence and propose a scan compensation method to design an ultra-broadband absorber with ultra-wide-angle and polarization stability. For realization, a dual-section dielectric layer is introduced to improve the input impedance, while magnetic material is primarily employed to mitigate frequency shift under oblique incidence, achieving much superior absorption performance of transverse electric and transverse magnetic waves at large incident angles. Integrating resistive surfaces, dielectric layers, and a grounded magnetic layer, an ultra-broadband and ultra-wide-angle microwave absorber is designed. Cube honeycomb structures are used to replace unavailable low-permittivity dielectrics to enable experimental validation. A prototype is fabricated, assembled and tested, and the measured results show that it achieves at least 90% absorption in 2.0-14.8 GHz under the normal incidence, with a fractional bandwidth of 152.38%. When the incident angle reaches 60°, the absorber maintains absorptivity at least 90% for both transverse electric and transverse magnetic waves. Measured results indicate that the designed absorber achieves ultra-broadband absorption performance with ultra-wide-angle and polarization stability.