Propagation of metric waves beyond optical range

A qualitative survey of tropospheric and ionospheric propagation in the frequency band 30-200 Mc/s. Theoretical considerations are limited to explanations of the basic principles involved. A knowledge of the easily recognized meteorological conditions associated with variations in tropospheric propagation is shown to be useful in short-term prediction of radio conditions. Owing to the random nature of such conditions, however, the extended ranges obtained will, in general, be disadvantageous because of interference problems between fairly widely separated transmitters. A selection of long-term observations over various land and sea paths, both tropospheric and ionospheric, is presented in graphical form and results discussed.