Low-Profile Ultrawideband Hybrid Absorber Using Carbon-Magnetic Material With Enhanced Absorption

In this letter, a low-profile ultra-wideband hybrid absorber (HA) is proposed with enhanced absorption efficiency of 97% in X band and Ku band based on step-impedance matching method. The proposed HA integrates multilayer graphene-based structure (MGBS) and magnetic material (MM) with stacked step-impedance substrate in an optimized configuration. The impedance calculations show that the step-impedance substrate significantly broadens the conditions for the proposed HA to achieve −15 dB reflectivity. Simulation results indicate that the reflectivity of the designed HA is less than −10 dB in the range of 0.75 GHz to 20 GHz and enhanced to −15 dB across 8 GHz to 20 GHz with a relative bandwidth of 185.5% and a thickness of $0.055\lambda _{\mathrm{L}}$ at the lowest operating frequency. Meanwhile, the oblique incidence response reaches 30° for TE mode and 60° for TM mode. Finally, a prototype is fabricated and measured results are consistent with the simulation results.