The Service Area of Medium-Power Broadcast Stations

According to modern standards for amplitude-modulated transmission in the band from 500 to 1500 kilocycles, the field intensities required to provide a good service in urban, residential, and rural areas are 25, 5, and 0.5 millivolts per meter, respectively. It is useful to be able to make a rapid preliminary assessment of the service area that will be obtained from a station in the considered band, for various values of power, frequency, and conductivity. Families of curves are given to show these relationships for the powers 1/5, 1, 5, and 25 kilowatts and for the three field intensities 25, 5, and 0.5 millivolts per meter. When the distribution of population in an area is known, it is then easy to find the station site which will give the most efficient coverage. The main factors and principles affecting the coverage of a station are discussed, and methods of dealing with practical problems are detailed.