Wave polarisation and its influence on the power available from a radio signal propagated through the ionosphere. Part 3: Two-hoop modes

In Pts. 1 and 2 of this paper, an analysis and numerical calculations were given for the fractions of power associated with linearly polarised components of the ordinary and extraordinary waves at a distant receiver, for single-hop sky-wave modes at medium and high frequencies. The present paper extends the analysis to the case of 2-hop propagation. It deals in particular with the effect of the midpath ground reflection. Expressions are given for the change in wave polarisation and loss of power during this reflection, and for the ionospheric coupling on the up going leg of the second hop. Numerical results for a number of sample paths are quoted and discussed.