Continuously polarisation reconfigurable antenna element by using liquid crystal based tunable coupled line

A polarisation reconfigurable microstrip patch antenna element is presented. The antenna includes a liquid crystal based tunable coupled line by which the antenna polarisation can be controlled. The prototype is fabricated in a similar fashion to LC displays resulting in a low-cost and simple fabrication compared to other tunable device fabrication technologies. The antenna operates at 13.75 GHz with a return loss of better than 10 dB and its polarisation is tuned continuously between linear and circular polarisations by applying a bias voltage from 0 to 40 V to the coupled line.