A NEW BOUNDARY INTEGRAL APPROACH TO THE DETERMINATION OF THE RESONANTMODES OF ARBITRARILY-SHAPED CAVITIES

We present an efficient algorithm to determine the resonant frequencie s and the normalized modal fields of arbitrarily shaped cavity resonat ors filled with a lossless, isotropic, and homogeneous medium. The alg orithm is based on the boundary integral method (BIM), The unknown cur rent flowing on the cavity wall is considered inside a spherical reson ator, rather than in free-space, as it is usual in the standard BIM, T he electric field is expressed using the Green's function of the spher ical resonator, approximated by a real rational function of the freque ncy, Consequently, the discretized problem can be cast into the form o f a real matrix linear eigenvalue problem, whose eigenvalues and eigen vectors yield the resonant frequencies and the associated modal curren ts, Since the algorithm does not require any frequency-by-frequency re calculation of the system matrices, computing time is much shorter tha n in the standard BIM, especially when many resonances must be found.