Automatic feeding arrangement based on theory of characteristic mode

The feeding design for achieving a certain radiation pattern using a single antenna is normally based on experience and trial-and-error procedure. Generally, feeding information includes the number, location, amplitude and phase of the ports. In this work, we propose a method for pattern synthesis of single antenna in any shape based on the theory of characteristic mode. By taking advantage of the far field orthogonality between the modes, the weighting coefficient of each mode in achieving the desired pattern is calculated. Thus, the synthesized current distribution is retained, from which the feeding information is roughly estimated. Moreover, the current is converted to voltage information across the edges, so that the feeding is automatically designed following the guidance. A thin strip is simulated as an example to show the procedure of feeding arrangement. The results show that the proposed method is quite effective in achieving required pattern specifications.