ALTERNATIVE CONTOUR TECHNIQUE FOR THE EFFICIENT COMPUTATION OF THE EFFECTIVE LENGTH OF AN ANTENNA

The scattering of a plane wave broadside incident to a dipole antenna with a symmetrically placed, open-circuited gap is treated. The induce d currents on the antenna are found by solving the electric-field inte gral equation by means of a Galerkin moment method. The resulting curr ent distribution is then used to compute line integrals of the scatter ed electric field along appropriate paths. The line integral is first evaluated directly across the dipole gap in order to compute the effec tive length, but severe convergence problems are encountered. This pro blem is due to the presence of charge singularities at the gap edges. Instead of incorporating the singular charge behavior into the basis f unctions, a line integral is evaluated along a path that alleviates th e convergence difficulties. This remedy is developed first for an elec trostatic case and then for the dynamic scattering problem.