Considerations on feed expressions for the numerical analysis of antennas

The integral equation obtained with a boundary condition at an antenna surface and axis, and the integral equation obtained using the axis current approximation are considered for the numerical analysis of antennas. The equations are calculated numerically for a linear dipole antenna applying the moment method. Consideration is given to assumptions of a slice generator, a finite gap generator, or an annular ring of magnetic current which are used as a feed. The effects on a numerical solution by the boundary condition, axis current approximation, and an assumption for an electric field of a feed region are investigated.