Polarization effects on the modeling of antenna transfer function in HF communication

The polarization of an electric signal changes as it traverses the high frequency channel due to the anisotropic nature of the transmission medium. Birefringence of the transmission medium causes the signal to split into ordinary and extraordinary modes, and each mode possesses its unique polarization which affects the design of the receiving antenna. Simulation results for polarization factors and received signal amplitude in the case of a tripole receiving antenna are presented as a function of transmitting frequency, geographical position of the receiver and direction of arrival (DOA) of the signal passing through the HF channel. Modeling of the electric field intensity received by the tripole antenna in terms of the polarization of incoming signal and ground reflection coefficients is also presented. The effects of antenna structure, ground properties, DOA and transmission frequency on the complex radiation pattern of the receiving antenna are discussed.