Wireless Waves

Radio Record, Volume II, Issue 9, 14 September 1928, Page 11

Wireless Waves

Influence of Refraction OR some time after radio communieation was first effected it was thought that the wireless waves travelled in straight lines. When, however, reception was accomplished over longer distances it was realised that there existed what is now known as the "heaviside layer." It was already known, however, that the radio waves’ did travel horizontally for a short distance, and the natural and correct solution was reached that the waves were transmitted in every direction and _ that those projected upwards were deflected by the "layer" to some spot at.a greater distance on the earth’s surface from the transmitting station. With the acceptance of this theory came two important discoveries-the obvious one, that of "skip-distance," and the second, the cause of "fading" which was due, according to Professor Appleton, to the simultaneous reception of two sets of waves, the horizontal and the deflected. ‘THE next notable discovery to be made was that the height above ground of the layer varied according to the time of day or night, an increase of 100 per cent. being apparent on some nights. This naturally makes a great deal of difference to DX (long distance) reception, for, the angle of incidence on the layer is equal to the angle of deflection, e.g., waves striking at an angle of forty-five degrees would be reflected at the :1m. angle. From this is may be seen that, theoretically. reception at night should be possible over twice the "daytime" distance. T will be seen that many of what are sometimes regarded as extraordinary phenomena are really the outcome of natural functions, and it is with the general appreciation of this idea that DX reception will grow more and more in the publie favonr.