Comparison of mobile radio transmission at 150, 450, 900, and 3700 mc

Based on a series of experiments, a comparison is made of the transmission performance of 150, 450, 9OO, and 3700 mc in a mobile radiotelephone type of service. This comparison indicates that 450 mc is superior transmissionwise to the presently used 150-mc band in urban and suburban areas. In fact a broad optimum in performance falls in the neighborhood of 500 mc. It is concluded that this range of frequencies would be well suited for providing coverage to meet the large scale needs which are anticipated in and around metropolitan areas. Although higher frequencies are less desirable, the tests indicate that 900 mc is somewhat to be favored over 150 mc from a transmission standpoint if full use is made of the possible antenna gain. Above this frequency, transmission performance falls off even assuming the maximum practical antenna gain. Transmission at 3700 mc suffers an additional impairment in that the fluctuations in received carrier level occur at an audible rate as the mobile unit moves at normal speeds. It is concluded that while transmission above roughly 1000 mc for these services is not impossible, it would be decidedly more difficult to employ these frequencies satisfactorily.