Oblique Incidence Performance of Microwave Absorbers Based on Magnetic Polymer Composites

Oblique incidence properties of the reflection coefficient of a multi-layered (or single-layered) metal-backed magnetic absorber (MA) are analyzed in terms of the input impedance. Constant input impedance, almost independent of the incident angles and polarizations, is achievable for most MAs. Thus, the incidence angle restriction for a specified level of polarization-independent reflection in most MAs can be deduced. Preconditions of the law are also discussed. Experimental results confirm both the law and its application for absorption design.