  A strong increase of the reflection loss (from 25 up to 35 dBs) and an
extension of the absorption bandwidth up to 20% under far-field real radar
conditions are experimentally reported in this work by creating a functional
bilayer system. Each layer consists of a composite material, typically a
dielectric matrix filled with magnetic entities (powder or wires). Combining
the two types of materials into a bilayer structure has shown unprecedented
improvements in microwave absorption capacities compared to the former
absorption of each layer. The potential of random magnets to create thin
broadband absorbers is also demonstrated. The capacity to improve the shielding
behavior is strongly related to each layer's permittivity, permeability, and
thickness. This provides strong control over the design of novel materials for
stealth applications.
