Key points are not available for this paper at this time.
In this article, the size of antenna Fresnel and Fraunhofer field regions are systematically derived starting from a general phase factor representation of the scalar diffraction theory. This is done by first expressing the phase of an arbitrary aperture field in a Taylor series in terms of a small parameter and then by subsequently imposing appropriate conditions for the Fresnel and Fraunhofer regions.
Selvan et al. (Wed,) studied this question.