A continuation method for identification of the natural frequencies of an object using a measured response

According to the singularity expansion method (SEM), the late-time electromagnetic field scattered from a finite sized conducting body is represented as a sum of damped sinusoids (natural modes). An important problem involves the extraction of the natural frequencies from a time domain measurement of such a scattered field. It is desired to find a function with certain characteristics which 'best fits' in some way the measured data. This problem is known to be ill-conditioned. The present investigation is concerned with a method for solving the problem with the aid of a regularization process. This approach makes it possible to change the ill-conditioned problem into a well-conditioned one with a sufficiently similar solution.