An Angularly Stable Wideband Low Profile Single-Layer Linear to Circular Polarization Converter for Millimeter Wave Satellite Communications

This paper presents a wideband linear-to-circular polarization (LP to CP) converter, utilizing a single-layer substrate and offering exceptional angular stability. The proposed converter achieves a generous 3-dB axial ratio bandwidth of 29% within the frequency span of 29.5-39.5 GHz. The unit cell dimensions for the LP to CP converter are 0.38λ x 0.38λ x 0.15λ (λ corresponds to the frequency of 30 GHz). Notably, the design demonstrates remarkable angular stability, reaching 50° and 60° for y and x-polarizations, respectively. To enhance practical utility, we integrated a wideband Vivaldi antenna with the LP to CP converter, resulting in a wideband CP antenna. The wideband CP antenna exhibits an axial ratio and 1-dB gain bandwidth of 16.5% and 12.5%, respectively. This wideband CP antenna can serve as a reference antenna for measuring CP characteristics and serving as a feed source for high-gain transmitarrays.