Calculation the phase center positions of linear and flat antennas

For the antenna which are a part of phase direction finders and interferometers, it is necessary to define spatial position of the phase centers (PHC) if those are available. In most cases PHC at many antennas is absent. Nevertheless, at work of the phase measuring radio systems based on measurement of a difference of phases (or delays) the signals coming from any source to carried antennas the PHC approximate situation in limited angular sector should be known.