Dielectric-Loaded Ultrawideband RCS Reduction Structures

A novel yet geometrically simple radar cross section suppression structure is proposed. Unlike designs fostered in prior works, which contain multiple elevated metal layers, the proposed configuration is only accomplished with a dielectric superstrate. Dielectric loadings of different properties such as permittivity, loss tangent, and thickness are applied to form phase cancellation structures. Contrary to structures based on resonant elements, the proposed constructs are electrically large and are made of homogeneous loadings. A high-frequency method is developed to explain how the ultrawideband backscattering suppressing feature is accomplished. Since it assesses structure reflection properties in a timely fashion with the results comparable to the ones acquired from full-wavelength tools, design optimization can be carried out via grid search. One design exhibits a 4.09:1 bandwidth ratio of 10 dB backscattering reduction for normal incidence, while another achieves a 70% bandwidth of 20 dB reduction. Angular domain performances were also researched. By adopting either the conventional checkerboard pattern or our previously developed random patch pattern, strong backscattering lobes can be avoided near the boresight region. Performance verification via measurements on prototypes is also provided.