This paper presents a hemispherical Luneburg lens, which provides high directivity, ~26.8 dBi, steerability up to +90o degrees and yet low side-lobe level within the Ka-band. A conical horn antenna is located at the focal point of the lens acting as the source. Its E-field is a superposition of TE and TM waves with equal magnitude. CP can be obtained by retarding one of the components with respect to the other by odd multiples of 90. Traditionally, quarter-waveplates with anisotropic in-plane permittivity have been used to achieve this effect at optical frequencies. As an initial approach, an ideal quarter-waveplate whose permittivity map is designed to minimize reflections in the direction of propagation whilst providing the required phase-shift for LP to CP conversion in the Ka -band is considered. The combined converter-antenna system yields an axial ratio of 1.3 dB albeit suffering from a narrow bandwidth and low angular stability.
|Publication status||Published - Oct 2017|
|Event||38th ESA Antenna Workshop: Innovative Antenna Systems and Technologies for Future Space Missions - Noordwijk, Netherlands|
Duration: 3 Oct 2017 → 6 Oct 2017
|Conference||38th ESA Antenna Workshop|
|Period||3/10/17 → 6/10/17|