Adaptive frequency sampling of scattering parameters obtained by electromagnetic simulation

In order to obtain the frequency response, a considerable amount of computation time in electromagnetic simulation is spent on the evaluation of a particular electromagnetic quantity in a user given number of discrete frequencies. The total number of, method of moments, simulations has been limited by using a rational function approximation based on derivative information of that quantity. This technique was used in order to obtain the far-field or induced current of antenna or scattering problems. Little has been done or published on adaptive frequency sampling, i.e. an algorithm for selecting additional frequencies in regions where the approximation exceeds some error measure, and for maximising the information provided by each new sample point. We propose general scheme based on the residual errors of the derivatives. The applicability of this scheme is illustrated with some well chosen examples. In these examples, the S-parameters of microstrip planar structures are calculated by a full-wave electromagnetic simulation.<>