Exact Formulas for the Determination of Antenna Local Phase Center

This paper presents exact formulas for the calculation of antenna local phase center. It will be shown that the knowledge of equivalent current distribution on an arbitrary radiating aperture allows the determination of phase center exact position. We will prove that the transverse coordinate (with respect to the observation direction) of phase center can be interpreted as the electromagnetic barycenter of the electric and magnetic current distributions, whereas (with respect to the observation direction) can be considered the electromagnetic equivalent of the momentum of inertia. Numerical results on the equivalent aperture distribution of a pyramidal horn antenna are presented to validate the technique.