A few widely used primary incident wave models for pyramidal horn antenna a
nalysis are compared on the basis of gain calculations. The analysis is bas
ed on edge-wave diffraction theory, as presented in a recent publication, w
ith some modifications made to the underlying theory, It is shown that thes
e models agree well for high-gain horns with small flare angles, but that t
he differences are more profound for lower gain horns, where the flare angl
es are larger. The accuracy of the various models are studied by comparing
the results to actual measurements. The respective effects of amplitude and
phase variation in the primary incident wave are also illustrated.