V-Band Fully Metallic Geodesic Luneburg Lens Antenna

Antennas in emerging millimeter-wave (mm-wave) applications are often required to have low losses and produce a steerable directive beam. These properties are achievable with fully metallic geodesic Luneburg lens antennas. In this communication, we report the first experimental verification of a geodesic Luneburg lens antenna in the V-band. The designed lens antenna is fed with 13 waveguides providing beam switching capability in a 110° range. The lens is implemented in the parallel plate waveguide (PPW) technology. The antenna is manufactured in two pieces, and a tolerance analysis indicates that gaps between the pieces can cause a severe performance degradation. Based on this tolerance analysis, two measures are taken to alleviate the manufacturing tolerances for the prototype. First, electromagnetic band gap (EGB) structures are placed around the feeding waveguides. Second, the electrical contact between the two pieces is improved in critical regions. Two prototypes are manufactured, one without and one with the extra measures implemented. The measured radiation patterns of the prototype without these measures have high side lobes and low realized gain compared with the simulation. The measurements of the robust version of the prototype agree well with the simulations and demonstrate the applicability of geodesic Luneburg lens antennas for applications in the V-band.