Development of a Planar LTCC GRIN Lens for 60 GHz Open-Ended Waveguide Antenna

This study deals with the design, realization and evaluation of a gradient index lens (GRIN) made of low-temperature cofired ceramic (LTCC) for millimeter-wave communication systems at a frequency of 60 GHz. The LTCC GRIN lens presented here utilizes a radial refractive index profile achieved by varying the dielectric properties within the LTCC structure by punching 100 μm holes in the green LTCC sheets. We present the optimization of the refractive index gradient using zones within the LTCC structure, the simulated radiation patterns, the steps of the LTCC fabrication process and the experimental verification of the lens performance. The fabricated WR15 waveguides with lenses are characterized in an anechoic chamber and show an antenna gain of 16.6 dBi at 60 GHz. The experimental results confirm the theoretical predictions very well and show a significant improvement in beamforming and gain.