An early-time analysis of ellipsoidal reflector antennas with a transient-step feed´s radiation for near-zone IRA applications

In this paper we present an early-time transient analysis of electromagnetic (EM) radiation of a perfectly conducting ellipsoidal reflector antenna which is fed by a spherical wave radiated from a feed with a cosine-tapered pattern and a transient time-step response. A transient-step response of the feed´s radiation is considered because it will produce an impulsive response near the second focus of the ellipsoidal reflector, which is very interested in the applications of impulse-radiating antennas. This TD solution is in a closed form and remains valid both near and far from the reflector, and can be used via the convolution theorem to efficiently obtain the early time transient fields generated by the same ellipsoidal reflector antenna when it is illuminated by a realistic finite-energy pulse which emanates as a spherical wave from the focus.