Scattering of EM wave by a narrow gap in a grounded dielectric layer

The authors approximate the total electric field in the discontinuity region with the electric field in a zero-width gap, and then calculate the first- and the second order iterative approximations to that field, as well as the far zone field, for a narrow gap. The approximate results agree very well with the MoM (method of moments) EFIE (electric field integral equation) solutions. The first-order approximation to the far field is expressed in a closed form in terms of elementary functions, and the second-order is expressed as an integral representation. However, the MoM requires calculation of the matrix elements by integration followed by solution of linear equations. Thus, the approximate method is much more computationally efficient than the MoM.<>