Combined phase center of electromagnetic horn in Cassegrain antenna

The definition of the combined phase center is given, the best choice of the planar cut for the combined phase center is presented, and the relationship between the combined phase center and the two principal plane phase centers is shown. As an example, the phase centers of a narrow-flare-angle corrugated horn are computed; the semiflare angle of the horn is 10.18 degrees and the length of the horn measured in wavelength is 12.52. It is demonstrated that the phase center in the phi /sub 0/=45 degrees plane can be used as the combined phase center for the horns holding a nearly symmetric pattern, and the combined phase center lies in the middle of the two principal plane phase centers, which is valid for both the near- and far-field cases.<>