Tuneable Polarisation Agnostic Reflectarray Element at mmWave Using Polymer Dispersed Liquid Crystal

A reflectarray element operating at 73 GHz is designed using polymer dispersed liquid crystal (PDLC) to allow tuning of the reflected phase. Liquid crystals allow low-loss tuning at mmWave frequencies, but add complexity to the fabrication process. PDLCs trap pockets of liquid crystal in polymer, simplifying fabrication at the cost of reduced birefringence in permittivity. This paper proposes and simulates a polarisation agnostic element design achieving 200 degrees phase change with only 2.1 dB magnitude variation using PDLCs by using a slotted, rotationally symmetrical unit cell with two closely spaced resonances.