THE CAUSE OF FADING

Radio Record, Volume I, Issue 28, 27 January 1928, Page 5

THE CAUSE OF FADING

4 REMARKABLE PHENOMENON. — The "radio roof," an ionised region in the upper atmosphere that causes radio concerts to wax and wane, is about 169 miles above the earth during daylight, and as night falls the level of the "roof" climbs as high qs 400 miles, according to observations described recently at New York by H. A. Heising of the Bell Telephone "Laboratories, who reported the findings at a ireeting of the Institute of Kadio Engineers. ‘ ._ He said measurements of waves between 57 and 111 metres in length revealed that the invisible ceiling rises at a rate of aout six miles a minute and falls at the rate of twenty miles & minute. ‘This unstable surface in the sky acts as a mirror and causes the ethereal signals to fade.