The phase velocity and attenuation of audio-frequency electro-magnetic waves from simultaneous observations of atmospherics at two spaced stations

Abstract

Radio-atmospherics of known origin were recorded on magnetic tape from two broad-band receivers 285 km apart in the United Kingdom, and, from photographs of the waveforms, the Fourier phase and amplitude spectra of the pulses were computed. This enabled the phase velocity and attenuation of radio waves in the frequency range 40 c/s–10 kc/s to be calculated. Observations were made under both daytime and night-time ‘Quiet Sun’ conditions of propagation. Where possible, the results are compared here with those of other workers. Attenuation rates greatly in excess of previous measurements have been found, particularly in the 2–3 kc/s ‘absorption band’, and the departure of the phase velocity from c is, in general, less than that shown by other workers. Interpretation in terms of models of the lower ionosphere is to follow in a later paper.