Abstract: The transient current of wire antenna or scatterer is calculated with a semi-analytic method. By integrating the electric field integral equation and th e approximate solution, a frequency-domain iterative solution is obtained. Then the inverse Fourier transform is performed to obtain the time-domain iterative solution. Compared with numerical methods, this method is easier to implement n umerical computation. The numerical results of wire antenna and scatterer obtained by Feko verify this method.