Spherical wavefunction analysis of radiation from the pyramidal horn
The pyramidal horn may be approximated as a quasi-pyramidal horn if the flare angles that describe it are measured from the same point. The quasi-pyramidal horn model is analyzed using spherical wave functions. Only the dominant TEr01 mode is considered. To simplify the boundary condition it is useful to consider the horn enclosed by a perfectly conducting sphere concentric to the horn apex. A finite spherical wave expansion (SWE) is used to describe the fields outside the sphere, with only outgoing waves needed. A comparison between the predicted and the measured far-field E-plane (φ = 90°) patterns was made with good agreement. Comparison with E. V. Jull's results (1981) shows that the SWE method is more accurate in predicting the radiation pattern than the aperture integration method.