79 GHz Meandering Enclosed-coplanar Variable Delay Lines in Liquid Crystals Encapsulated within Independent and Shared Cavities

New meandering enclosed-coplanar waveguide (MECPW) millimetre-wave variable delay lines are designed with a bent core line interfacing a shared layer of highly anisotropic liquid crystals (LC) GT7-29001. Impacting tunable dielectric’s volume, phase-tuning range, cost, and insertion loss, two device designs are proposed, featuring an independent cavity, and a shared cavity, respectively. Up to 5°/dB of improvement in the figure-of-merit is foreseen at 79 GHz by using the shared-cavity design, with a further benefit of reducing the required LC filling volume by 1.6% per device. The size and cost reductions are promising for mass production targeting a phased array feed.