Analysis of near-field radiation from an open-ended rectangular waveguide

On the basis of Hertz's potentials technique the radiation characteristics in near and intermediate zones of single mode and oversize rectangular waveguides have been investigated. The bounds of far-field zone have been determined for small in comparison with wavelength waveguide radiators. For these small radiators the classical expressions for far-zone can be applied. The influence of the effects of electromagnetic mode reflection and transformation at the antenna aperture on radiation characteristics in near-zone has been analyzed