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 induced currents on the antenna are found by solving the electric-field integral equation by means of a Galerkin moment method. The resulting current distribution is then used to compute line integrals of the scattered electric field along appropriate paths. The line integral is first evaluated directly across the dipole gap in order to compute the effective length, but severe convergence problems are encountered. This problem is due to the presence of charge singularities at the gap edges. Instead of incorporating the singular charge behavior into the basis functions, a line integral is evaluated along a path that alleviates the convergence difficulties. This remedy is developed first for an electrostatic case and then for the dynamic scattering problem