Pattern control of a 1/4 λ monopole antenna on a handset by passive loading

The radiation patterns of a 1/4 λ monopole antenna for a portable handset deteriorate when the size of the handset is about a wavelength. In Japan, digital cordless telephone system PHP (Personal Handy Phone) will be operated at 1.9GHz band. Therefore the control of its patterns and the quantitative prediction of the radiation patterns are important for the design of the antenna for a portable handset. First, the authors show that the desired radiation patterns can be obtained by controlling the radiation patterns of a 1/4 λ monopole antenna on a handset using a passive load connecting two conducting boxes in the handset. Second, the radiation patterns of a optimum passive load have some preferable characteristics. The handset is modeled by two finite conducting plates which are connnected by a passive load. The radiation patterns for various passive loads have been calculated using the method of moments of rectangular patch modeling and the results have agreed well with the experiments