Magnetic tuning of a microstrip patch antenna fabricated on a ferrite film

A square, single-feed patch, fabricated on a ferrite film, that produced orthogonally polarized, well-formed radiation patterns is described. The application of a small in-plane magnetic field tuned the frequency, and hence phase, of one polarization only. Prior work on patch antennas fabricated on bulk ferrite substrates demonstrated magnetic tuning, but only linear polarization was obtained. The results indicate that (1) thin ferrite films, which are monolithically integrable, may be useful for a magnetically tunable antenna, and (2) the radiation polarization of the patch can be varied by the application of a small in-plane magnetic bias field.>