On the relation between the element correlation of antennas on small terminals and the characteristic modes of the chassis

In this paper we present some basic investigations to show the relation between the element correlation of antennas on a common small terminal and the characteristic modes on the chassis excited by those antennas. The results show, that the characteristic of an antenna array is heavily affected by the weighted characteristic current modes of the chassis. The actual mode and its weight, however, depend on the dimensions of the chassis and the locations of the antenna elements for a given frequency. In case of a two antenna systems the effect of the common ground plate on the element correlation can be minimized by locating the antennas in such a way that both excite the same mode 180° out of phase.