Design, Fabrication, and Measurement of a Hemispherical Multi-Layer Band-Pass Frequency Selective Surface

A hemispherical multilayer wide-band (7-13 GHz) band-pass frequency selective surface (FSS) is reported. A new design technique based on a Goldberg discretization and unit cell scaling technique is introduced to accommodate the curved profile of the FSS. The FSS is additively manufactured by sequentially printing dielectric layers and metallic patterns until 3 patterned silver-ink surfaces are integrated within a 4.5 mm (${λ_0}/6$ at 10 GHz) thick ABS hemispherical radome. The diameter and the height of the realized hemispherical FSS are around $5{λ_0}$ and $3{λ_0}$ respectively. Measurements demonstrate a roughly 1.7 dB insertion loss in the passband and 15-20 dB rejection in the stop-band. Additionally, a new postprocessing technique is used to suppress the effects of edge diffraction in the measured transmission spectrum. The design process, manufacturing technique, and measurement postprocessing represent novel advancements enabling future conformal frequency selective surfaces.