Broadband Absorber With High Angular Stability Based on Magnetic Material

This communication proposes a broadband absorber that exhibits excellent angular stability. A unit cell is formed by stacking a modified magnetic material layer, an air spacer layer, and a grounded magnetic material layer. An equivalent circuit model (ECM) is established for the absorber, studying the surface impedance and the conditions, in which the absorption rate surpasses 90% at various incidence angles. Furthermore, a prototype is fabricated, assembled, and measured to confirm the operation feasibility of the absorber. The experimental results demonstrate a stable absorption band (|S|(11) <= -10$ dB) between 2.4 and 7.3 GHz under normal incidence, with a fractional bandwidth (FBW) of 101% and a relative thickness of 0.099 lambda(L). When the incident angle theta reaches 60 degrees, the absorption performances remain the same for TE- and TM-polarized oblique incidences. The measured results demonstrate that the absorber attains an absorption rate of over 80% within the +/- 70 degrees airspace range.