Selective excitation of characteristic modes on small terminals

In this paper we present a concept for the selective excitation of different orthogonal modes of a small terminal chassis. The concept can be used to realize an efficient multi port antenna system in order to enable MIMO (Multiple Input Multiple Output) for small terminals. The idea is based on the TCM (Theory of Characteristic Modes). The selective excitation of these modes is achieved by sets of couplers that are located at specific positions on the terminals´ PCB (Printed Circuit Board). Passive matching circuits care for a good impedance match to 50 Ω. As a result it is demonstrated that nearly perfect de-correlation of the ports of the multi antenna system can be achieved.