Theoretical limitations on shielding and reflective properties of microwave absorbers

In this paper we investigate theoretical limitations of the reflective and absorptive properties of a single-layer passive homogeneous microwave absorber that follows solely from the boundary conditions applied to the flat plane surface which separates the air (vacuum) and absorber half-spaces. Dielectric, magnetic and magneto-dielectric passive absorbers have been considered. Following this, examples of multi-layer absorber designs, which help to overcome the above limitations have been investigated and compared with a single-layer case.