Transient Field Calculation of Aperture Antennas for Various Field Distributions Over the Aperture

This letter presents a time-domain method of near-field calculation for circular plane apertures of various field distributions. The method allows getting analytic forms presented in inverse trigonometric functions. New formulas for transient near field are derived in this letter for circular plane apertures of electric field falling down to edges of the aperture. The behavior of the transient near field of a circular aperture with distributions tapered toward the edge is explained.