Field-Strength Survey, 52.75 Megacycles from Empire State Building

This paper outlines the results of a field-strength survey which was conducted on the audio-frequency channel of the National Broadcasting Company television transmitter, operating on a frequency of 52.75 megacycles. The test transmissions were horizontally polarized. Continuous mobile recordings were made over land in a number of directions along radials from the transmitter out to the limit of the receiver sensitivity, which was reached at a distance of 70 or 80 miles, at a field strength of about 10 microvolts per meter. From the recorded data, coverage maps based on average field strength were drawn. The maps are supplemented by graphs showing the deviation to be expected because of irregular terrain and refraction effects at the greater distances. In general, local variations of 20 decibels in field strength were caused by irregular terrain, buildings, and other objects.