Kennelly-Heaviside Layer Studies Employing a Rapid Method of Virtual-Height Determination

This paper describes a new method of determining the virtual height of the ionized regions by visual observations of the received pulse pattern on a cathode ray oscillograph tube, both for single frequencies and for two frequencies simultaneously. A résumé of the data obtained during observations of some three hundred hours is given. The frequencies used for these tests were 1604 kc, 2398 kc, 3256 kc, 4795 kc, and 6425 kc. A number of the tests included measurements made upon two frequencies in rapid rotation. The more important results may be summarized as follows: (1) On a large number of occasions during the night, a phenomenon has been observed apparently indicating an increase in the density of ionization in the lower layer. This is important because the ionization is usually assumed to decrease during the night hours. (2) Reflections are often observed simultaneously from both ionized layers. An explanation of this phenomenon is given. (3) The virtual heights of the reflecting layers are rarely duplicated from day to day for a given time and frequency. (4) Large numbers of multiple reflections are frequently obtained representing a path distance of over 5000 km for the last reflection. This fact indicates that the multiple-hop mode of propagation is probable for long-distance transmission.