부산대학교 도서관

A method of evaluating Fresnel zone radiation fields is studied for circular and elliptic aperture antennas which is illumated with an arbitrary aperture distributions. Fresnel zone field is represented by a series of generalized Lommel functions of two parameters defined here. It is shown that the generalized Lommel functions with any degrees and orders may be derived from the original Lommel functions [1] using the recurrence relations. The validity of the expressions is verified numerically by comparing with those obtained from the method by Sun and Rusch [2] and from direct numerical integrations. This method may also be applied to predict the far field pattern of offset typed parabolic reflector antennas [3] . The three dimensional pictures of Fresnel patterns for circular apterute with tapered illumination as well as uniform distribution are obtained.