Compact Features of a Metamaterial Based Microwave Absorber

Microwave absorbers are widely used in electromagnetic compatibility problems to reduce the mutual interactions between different devices, in antenna applications to reduce the back-radiation and to improve the radiation pattern of a radiator, in stealth problems to reduce the radar signature of a given object, in the measurement of the scattering features of objects and antennas, etc. The design of a microwave absorber usually consists of a trade-off among some major contrasting goals, such as reduced electrical dimensions, wide angular bandwidth, and wide frequency bandwidth. Recently, we have presented a new idea for a compact absorber, consisting of a metamaterial complementary resonant bilayer. In this layout, a resistive sheet with a given resistance is placed at the interface between two materials with oppositely signed constitutive parameters. If the resistance of the sheet is chosen in a judicious way, the presence of the resistive sheet does not sensibly weaken the resonance arising at the interface, and, thus, allows maintaining sufficiently high field amplitudes at its location, absorbing most of the impinging power. Since this resonance is independent on what surrounds the bilayer, the absorber does not need any metal backing and may also be electrically very thin. We have shown theoretically that this configuration might in principle be less affected by the incidence angle of the incoming electromagnetic wave and may exhibit also a reduced dependence on the field polarization. Some new theoretical results, giving further insights into the physical phenomena characterizing this compact absorber, and foreseeing some possible practical applications will be presented at the conference