Electromagnetic 2.5-dimensional forward modelling with a boundary integralformulation

An effective and accurate technique for the numerical solution of 2-D elect romagnetic scattering problems with 3-D sources is presented. This solution introduces a set of the usual boundary integral equations and uses a scala r Green's function. In this scalar version, the unknowns of the problem are the boundary values of the longitudinal fields and their normal derivative s in the Fourier domain. A generalization of the usual boundary integral fo rmulation enables us to handle a large class of models composed of piecewis e homogeneous domains, including contiguous domains, Multiply-connected dom ains and unbounded domains. This formulation involves the solution of a sys tem of linear equations, and results in a significant saving in computation time in, comparison with other rigorous methods. The requirements for the numerical implementation of this solution are desc ribed in detail. Numerical tests were carried out using the important examp le of electromagnetic tomography. The specific symmetry properties of the r esponse function in this case are illustrated. Numerical accuracy is verifi ed over a large frequency range, up to 1 MHz.