A 3-D-Printed Multibeam Dual Circularly Polarized Luneburg Lens Antenna Based on Quasi-Icosahedron Models for<i>Ka</i>-Band Wireless Applications

This article presents a multibeam dual circularly polarized (CP) Luneburg lens (LL) antenna based on quasi-icosahedron (QICO) models. The lens is sliced into multiple shells and each shell comprises of several triangular unit cells, and then the permittivity variation is achieved by manipulating the wall thickness of each triangular unit cells after the QICO discretization. Such a QICO model is firstly proposed to be used in LL design, which not only makes the lens mechanically robust and manufacturing-friendly (no support is needed in the processing) but also enables the antenna to be polarization insensitive and thus can sustain CP beams very well. A wideband ridged waveguide feed is selected to initiate left-handed CP (LHCP) and right-handed CP (RHCP) beams simultaneously. To prove the concept, a prototype was fabricated using 3-D-printing (3DP) technologies. The measurement results reveal an overlapped bandwidth of 33.1% (26.5-37 GHz) in terms of reflection coefficients lower than -10 dB and axial ratios smaller than 3 dB. Five LHCP and five RHCP beams with gains of 19-21.2 dBic and couplings lower than -20 dB are also demonstrated.