Practical limitations of the broadcast allocation structure

To give the radiobroadcast listener maximum service is an important problem in which the frequencies available, characteristics of the receiving set, phenomena of transmission of radio waves, area to be served, and density of population in the area must be considered. Broadcast stations in the United States are of 2 main classes, clear channel and duplicated channel, and are allocated in frequency to prevent interference between stations in the same area. Short-wave broadcasting has additional limitations because of natural phenomena.