Thin, Lightweight, Broad Band Microwave Absorbing Material

Existing X/Ku band absorbers are limited in several ways. Multilayer or graded foam stacks are thick (.375") and are not able to meet the rigorous outdoor naval environment. Magnetic multiband materials are thinner (.175") but generally are heavy (1.5 psf). Both materials suffer from performance degradation as the impinging energy is at a high angle of incidence. A novel material is proposed that will be thin, lightweight and perform at high angles of incidence as well as attenuate surface currents. The key to the enhanced performance will be the introduction of anisotropy into the material. The material will have embedded fibers with a preferential dispersion in the Z direction (perpendicular to the surface). This will lead to eps (xx) = eps (yy), not equal to eps (zz). In such a material, the effective surface could be tuned to polarization and angle of incidence in such a way as to have good properties for both polarizations, out to large angles of incidence, and have relatively good surface wave absorption properties. This is not possible using isotropic dielectric absorbers. An analytical optimization of fiber length and dispersion will be performed as well as research into the materials and fiber loading techniques required to meet the analytical design.