Polarization reconfigurable antennas for HF MIMO communications

Over-the horizon wireless communications within the HF-band is subject to the Faraday effect where the polarization of electromagnetic waves rotates due to the ionization and geomagnetic interactions. This results in further signal loss and fading in addition to the usual multi path propagation fading. In this work, based on the standard Watterson HF channel model, a new HF-MIMO fading channel model is developed that takes into account the radiation patterns of transmit and receive antennas, and then the impact of polarization rotation and antenna polarization mismatch on the HF channel capacity is investigated. The case where the transmit and receive antennas are capable of having multiple different polarization radiation patterns is studied, and an the HF channel capacity resulting from an ideal polarization matching algorithm that can track the polarization rotations is evaluated. Based on the simulations, it is observed that significant improvements can be attained by polarization reconfigurable antennas when used against the Faraday rotation induced polarization variations.