Vehicular antennas for 800 MHz mobile radio

A roof-top quarter-wave antenna, which is a good mobile antenna for the high VRF band (150 MHz) is not very useful for the 800 MHz mobile radio band (806-866 MHz) because the effective area at the higher frequency is less by a factor of about thirty. This situation is further aggrevated by the fact that the receiver sensitivities are reduced and propagation losses higher at the higher frequency. An additional complication is the 45 MHz bandwidth requirement for 800 MHz cellular mobile systems. These effects can be partially overcome by employing high gain antennas. However, Lee has made measurements that show that the expected high-gain antenna performance is not achieved at a mobile in an urban environment. He interprets this to be due to the spread of vertical incident angles from the horizon. This paper will discuss measurements made on an antenna modelling and an antenna pattern range of the, impedance/bandwidth characteristics, antenna gains and vertical patterns for typical vehicular antennas. These results are complemented with practically achieved "gain" measurements in the mobile urban environment. The paper concludes with a suggested type of antenna that could be used for this band.