Planar Multilayer Structure for Broadband Broad-Angle RCS Reduction

A broadband broad-angle radar cross-sectional (RCS) reduction measure applicable to planar surfaces is proposed. This novel structure contains several layers of randomly displaced metal patches and layers are spaced by a quarter wavelength. Specular reflection at normal incidence is suppressed by the phase cancellation technique. The reduction bandwidth is broadened by setting the layer surface area ratio based on binomial coefficients. Because the structure contains no absorbent material, metal surfaces are divided into small patches and displaced randomly to avoid reflection peaks beyond the boresight direction. The RCS reduction effect is validated via measurements in a far-field antenna range. Parametric studies and detailed discussions about this technique are conducted using simulation results computed from full-wave numerical tools, which include not only the specular reflection but also contributions from higher order scattering mechanisms. The proposed structure can be applied on planar target surfaces and has the potential to incorporate lossy dielectric loadings to reduce the structure thickness and suppress scatterings.