Abstract: The independent channel capacity obtained in a scattering environment is three times more than that gained in the free environment. The extra channel capacity is gained because there are six distinguishable electric magnetic states of polarization at a given point, rather than two as is usually assumed. According to the characteristics that the scattering environment in which HF radio transmission spreads is always changing, comparisons are made by testing the relations between the voice quality of the composite polar channel voice received by a printed helix antenna (loaded whip antenna in the terminal) and distance. After comparing horizontal polarization, vertical polarization with circular polarization in tone quality for transmitting at the same frequency and distance (within 200km), a relationship is given between tone quality and transmitting distance. The voice levels of all three different polarization antennas are above 1, which shows that the electric and magnetic polarizations received on the carriers are not single horizontal polarization or vertical polarization. The experiment shows that the reliability of HF mobile communication can be raised by transmitting or receiving the same message through different polarizations. Based upon this theory, a novel model of multiple polarization antenna system is presented.

Key words: electromagnetic polarization, HF mobile communication, helix antenna