Advanced Eigenvalue Tracking of Characteristic Modes

Eigenvalue tracking is a serious issue in the calculation of characteristic modes over a wide frequency range. Two commonly used algorithms in this regard are investigated and the drawbacks that typically occur during eigenvalue tracking are explained. We discuss the effect of the degraded modes in detail. A new algorithm is presented that overcomes these drawbacks in an innovative way. The new algorithm is explained in detail and investigated with respect to its numeric stability. A rectangular plate is used as a generic example to evaluate the tracking algorithms. Finally, a fractal antenna is evaluated as an advanced example.