Anomalous variations in phase path records

Abstract

Simultaneous records of amplitude and phase path of ionospherically reflected pulsed radio waves received on an E-W aerial under periodic fading conditions show sudden discontinuities in the phase variations, when the amplitude is a minimum. Under random fading conditions also, the sudden discontinuities, frequently observed in the phase variations, are always accompanied by an amplitude minimum. It is shown that when two signals with a phase path difference changing continuously are received simultaneously, the resultant phase of the combined signal changes rather slowly, and shows a discontinuity, when the difference passes through an angle of 180°. The phase path variations recorded at points separated by about 100 m, sometimes show variations in opposite directions. This has been interpreted as due to the changes in the direction of arrival of the downcoming waves.