hfss phase center í??ì??

I am working in an algorithm to calculate the phase center of an antenna (or the effective phase center). But the papers i have found have not been very useful.
The idea is to be able to obtain the phase center from the radiated far fields (E field) amplitude. (obtained in HFSS analisys.). I have passed more than tree weeks trying to find some previous attempts or some feedback in this topic. But I have not suceeded. (I have to build a matlab program)

First I need this algorithm and then I have to extend it to find a "surface" in order to find the possible positions (because it moves with the frequency change) of the phase center of an UWB antenna.

I know that the phase center will depend on the type of antenna, the geometry, the polarization, frequency. But to beguin I just need a first step to go from a general algorithm to a mor specific one.

I hope someone has an idea.

Thanks in advance.

You can take a look in following papers:
- Phase centre movement in linear phased array antennas
- Phase centre analysis of array antennas and its significance for microwave landing system
- The calculation of the phase center for spacecraft phased array antennas.

This papers talk about phased array antennas but the method can be applied to single radiating elements.

In you have more doubts, don't hesitate to contact me.