V.H.F. propagation by ionospheric scattering and its application to long-distance communication

The paper describes an investigation of the propagation of v.h.f. radio waves by scattering from the E-region of the ionosphere. The dependence of the characteristics of the received signal on frequency, distance and aerial directivity is examined, and observations are made on the diurnal and seasonal variations of the received signal strength; the results are discussed in relation to existing theories. Investigations are also described on the suitability of this form of propagation for the transmission of frequency-shift telegraphy signals, and for telephony signals transmitted by single-sideband amplitude modulation, and by phase modulation, of a carrier. A form of waveangle diversity reception which yields a substantial improvement in the performance of a telegraphy system is described. The possible applications of v.h.f. scatter propagation to commercial services are discussed.