High-frequency reflection from the aperture of a long E-plane sectoral horn

The result of Yee et al. (1968) for the parallel-plane TE/sub 10/-mode reflection coefficient, used in Jull's (1972) formulation for the reflection coefficient of a long E-plane sectoral horn, is replaced by the Boersma's (1974) corresponding result. At longer wavelengths, the expression that emerges displays a much better match with experiments than Jull's original expressions.