Antenna feed placement based on theory of characteristic modes

In this work, we present a procedure for automated placement of a coaxial feed. We apply the theory of characteristic modes to determine the excitation points on the antenna that give the highest radiated power. We illustrate the ability of the algorithm to find good feed positions with three test cases - dipole, Yagi-Uda, and a branching wire antenna. The procedure is most accurate for electrically small and intermediately sized structures, while it gives less reliable results for larger structures with multiple radiating modes because of the errors in the calculation of the eigencurrents.