Design of 3D broad-band and wide-angle absorber based on resistive metamaterial and magnetic absorbing material

A three dimensional broad-band and wide-angle absorber (3D BWA) was designed through a three dimensional resistive metamaterial in which a traditional magnetic absorbing material was added on top of the metallic backplane. Owing to the better magnetic loss performance of the magnetic absorber at lower frequencies and superior impedance matching effect and ohmic loss property of the resistive films at higher frequencies, the absorption can be extended to a wider band through their combination. Simulation result shows that the absorption of the 3D BWA is more than 90% in the frequency range of 3.7-40GHz at normal incidence, and it is in accordance with the experimental result. The absorption performance for each part of the 3D BWA was analyzed using electric field and magnetic field distributions, surface current distributions and Smith chart. For TE polarized waves of 3.7-40GHz, the absorption with the incident angles of 0°-60° is more than 77% . The absorption higher than 80% can be achieved under TM polarized waves of 4.2-40GHz as the incident angle changes from 0° to 60°. When the incident angle is 70°, the absorption is greater than 85% in the frequency range of 5.7-40GHz. Owing to the four-fold rotationally symmetric unit cell structure, the absorption spectrum under different polarization angles remains unchanged. These two characteristics make the designed absorber as a good candidate in stealth applications.