A variable polarization ferrite antenna

This paper describes a ferrite antenna that can produce any polarization on the Poincare sphere over the frequency range of 9.0 to 11.4 GHz by utilizing Faraday rotation and a quarter-wavelength phase shifter. All possible polarizations of the electromagnetic wave are achievable with this antenna which includes linear, circular and elliptical polarizations. Any tilt angle of elliptical polarization and any orientation of the linear polarization can be achieved as well. The polarization of the ferrite antenna can be electronically switched to a different polarization instantly without the use of moving parts. An automatic data acquisition system was designed and built to fully analyze the antenna´s characteristics. Measured data shows cross-polarization values of 35 dB, axial ratios less than 1.5 dB and VSWR<2.0:1.