Microstrip antennas utilising MEMS for reconfigurable polarisation states

A modern approach to an established technique is investigated for the electronic control of polarisation of microstrip patch antennas. The control is achieved by placing micro-electromechanical switches (MEMS) at appropriate locations in a patch antenna. The microwave MEMS are used to switch between open and short circuit conditions that allow reconfiguration of the modal fields. Changing the number and location of short circuit field regions changes the radiated field polarisation from linear horizontal to vertical, right hand circular or left hand polarisation. All of the polarisation states are obtained without changing the frequency of operation, input impedance or radiation pattern of the patch antenna. The antenna is fed with a single external feed network.