Convergence of moment-method solutions of the electric field integral equation for a 2-D open cavity

We study the problem of accurate numerical determination of the radiation a nd scattering properties of resonant structures by estimating the cavity mo de eigenvalues of the electric field integral equation for a two-dimensiona l open cavity. We obtain moment matrix condition number estimates for the T E and TM polarizations, and, by taking into account the quadrature error in troduced by approximate numerical integration of matrix elements, we show t hat the number of unknowns required to accurately resolve the cavity modes scales as the square of the electrical size of the cavity. (C) 1999 John Wi ley & Sons.