Vertical patterns of mobile antenna at UHF frequencies

Theoretical and experimental studies are made on radiation patterns of mobile antennas within a frequency range from 300 MHz to 900 MHz. To calculate vertical plane patterns of a quarter wavelength monopole and a half wavelength dipole located on an automobile´s roof, the theoretical model of an automobile body is employed in conjunction with GTD. The theoretical model consists of three perfectly conducting plates. It is ascertained from comparison between calculated and measured patterns that the effect of the body and the earth can be well examined with the theoretical model. It is demonstrated from the results of pattern calculations for the above two antennas that the radiation patterns depend largely on the configuration of the automobile body and the earth condition. The technique described in this paper is used for designing mobile antennas with a computer in the initial stage of automobile body design.