Geometric polarization and Faraday effects for VHF satellite communication links

In this paper we investigate the interactions between antenna orientations, propagation link geometry and Faraday rotation for a line-of-sight VHF satellite communication link. A key contribution is development of a three dimensional (3D) equivalent baseband model that incorporates link geometry, antenna radiation patterns and the rotation of the polarization of the radio wave as it passes through the electron plasma of the ionosphere in the presence of Earth´s magnetic field. Through simulations of an overhead pass for a low earth orbit (LEO) satellite in night and day ionospheric conditions, we characterize the combined effect of the link geometry and Faraday rotation. We show that Faraday rotation may in fact improve the channel quality. The power transferred from transmitter to receiver including Faraday rotation can be greater than that for a link with no Faraday effects. This occurs when the antenna orientation at the receiver is favourably aligned with the rotated polarization of the incoming radio wave.