An FSS-Integrated Low-RCS Radome Design

This letter proposes a novel radar-cross-section suppressing measure that is compatible with existing radome structures. It applies two layers of frequency selective surface made of cross element on top and bottom surfaces of the radome's dielectric slab. It works as a bandstop filter because incidence is mostly reflected in the cross resonant band. By setting the radome slab thickness as an odd multiple of a quarter-wavelength, the two layers form a phase cancellation structure and suppress returns. The radome functions normally provide that the antenna band is sufficiently different from the cross resonant frequency. Simulated and measured results validate the backscattering reduction feature. Matching and pattern characteristics of the underneath antenna are mostly unperturbed. Note that results also show that beyond the cross-resonant frequency, due to partial transmission, the suppressing bandwidth can be broadened with a proper radome-to-antenna ground distance. A 10 dB backscattering reduction bandwidth amounting to 25% can be achieved.