Propagation in the UHF-TV band

The Central Radio Propagation Laboratory of the National Bureau of Standards has been conducting a program of research at frequencies of 418 and 1,046 mc in conjunction with an extensive 100 and 200 mc program of measurements throughout the United States. This research program has revealed many aspects of the frequency dependence of propagation from 100 to 1,000 mc, including the attenuation with distance and the magnitude of signal strength variations. Reception of 1,046-mc transmissions 400 miles from Cheyenne Mountain, Colo. has been found possible at all times. By far the most important factor determining the available signal power available to the receiver in the uhf band is the effective absorbing area of the receiving antennas. This is illustrated by the use of the transmission loss concept in presenting the results of propagation studies. Transmission loss and its variability versus distance will be presented for a number of frequencies in the vhf and uhf bands as derived from the National Bureau of Standards propagation research program and an interpretation of the results will be given in terms of expected service and interference ranges in the uhf band.