Original improvements of TLM method

The use of the three-dimensional-TLM method is limited, first, by an excessive computation time and, secondly, by the variability of the results when the position of the point of observation varies. An original approach is described which improves the first point and avoids the second one. The resonant frequencies of the studied cavity are computed by applying Prony´s method to time variations of the electric energy located inside the cavity. Numerical results are given in the case of the ridged waveguide cavity.