A comparison between the antenna current green function and theory of characteristic modes

In this paper, we compare the procedures and practicality/complexity of the antenna current green function (ACGF) and theory of characteristic modes (TCM) when applied to antenna design problems. Some recent works on both methods are summarized. The ACGF is an analytical method that relies on the antenna current equation, that is why its application is limited. In TCM the main focus, thus far has been on the chassis behavior and excitation of the modes on the chassis. In real scenarios, the chassis can not be used as the main radiating element because it acts as a base to many electronic components and this will obviously effect the natural modes of the antenna.