Abstract :
A comparative study of 900-MHz, 450-MHz, and 150-MHz mobile radio propagation characteristics performed in Copenhagen, Denmark is described. The three systems were compared with respect to usable coverage area, flutter characteristics, and transmission quality. A statistical method was used for the determination of the coverage area, the limits of which are defined by the contour line corresponding to 20-dB noise quieting at 90 percent of the locations. Flutter patterns were photographically recorded, and simultaneous recordings of voice signals received on the three systems were made on magnetic tape. Concluded is that when corrections are made for differences in transmitter power, antenna gain, receiver sensitivity, etc., and when the propagation losses are assumed to vary with frequency like the free space losses, the coverage areas obtained will be nearly identical. The increased flutter rate at 900 MHz apparently does not affect the transmission noticeably, and it must be generally concluded that the 900-MHz band will provide as good mobile radio performance as any of the lower bands.
