Field Intensities beyond Line of Sight at 45.5 and 91 Megacycles

This paper presents the results of a field-intensity monitoring project initiated by the Federal Counications Commission during the summer of 1945. Field intensities on 45.5 and 91 megacycles from transmitters at Richfield, Wisconsin, were continuously monitored for a period of two months at Deerfield, Illinois, over a transmission path of 76 miles. The data is analyzed in terms of the average median field intensities and their diurnal variation. The number of hours of unsatisfactory broadcast reception due to fading is estimated for both frequencies, assuming representative transmitter power and receiver sensitivity. Comparison is made with similar analyses of data obtained by the Federal Communications Commission in the measurement of field intensities on 46.7, 83.75, and 107 megacycles at Andalusia, Pennsylvania.