Differential absorption measurements by a phase difference technique

Measurements of the phase difference between the signals from ionospherically propagated radio waves received on a vertical whip antenna and on a horizontal dipole at the same location are shown to lead to an estimate of the relative powers in the ordinary and extraordinary components when the propagation path is such that quasi-longitudinal approximations may be used. The technique is valid for incoherent signals, where the incoming waves are considered to be made up of many individual rays. When spaced antennas are used, an estimate of the mean difference in bearing angle between the ordinary and extraordinary components is possible.