Design and oblique incidence performance of a planar radome absorber

Design and measurement of a planar radome absorber under oblique incidence are presented. The structure is composed of a bandpass multilayers frequency selective surface (FSS) combined with periodic cylindrical-shaped absorbers. This configuration made the resulting structure transparent at the intended antenna operational frequencies (C-band) and absorptive at higher frequencies (X-band). The prototype has been fabricated with a dimension of 24.5 cm × 24.5 cm × 0.65 cm. Performance under oblique incidence (without the antenna) is investigated using NRL arch technique in the absorption band. Reflection less than -10 dB is maintained in the range of 8.5 GHz-11 GHz up to 40° incidence angle for incoming waves with perpendicular polarization. Under parallel polarization, the -10 dB reflection is achieved up to 50° in the range of 8 GHz-12 GHz.