title: Maximum far-field divergence angle of a plane source.
abstract: The far-field properties of a plane source with a constant phase distribution are presented. It is found, for the first time to our knowledge, that for any plane source the theoretical upper limit of the far-field divergence angle is shown to be 65.5°. This result is different from what previous propagation and diffraction theories predicted, and when the size of the source approaches zero, the far-field behavior of the plane source is also different from a spherical wave in half-space.
authors.forename: X
authors.initials: X
authors.lastname: Zeng
authors.forename: C
authors.initials: C
authors.lastname: Liang