On Modal Excitation Using Capacitive Coupling Elements and Matching Network

A resonant characteristic mode (CM) is useful for antenna design if it is properly excited and well matched to the source. In this paper, we consider the feed design for the excitation of the fundamental CM of a rectangular chassis. The tradeoff between the required number of capacitive coupling elements (CCE) and matching elements used for achieving a given antenna bandwidth is studied. The results reveal that in order to attain the modal bandwidth of the fundamental mode, the use of multiple CCEs with optimal placement and phase simplifies the required matching network.