A method for calibrating an antenna system having electronics and two or more passive antennas for connection to the electronics and two or more signal interfaces for use with a pilot signal. The method includes compensating for three major errors in order to find calibration offsets in a deterministic process. These errors are caused by differences between antenna interfaces, differences between signal interfaces and frequency margin, i.e., frequency offset, between main signal and accessory (pilot) signal. In the method, a calibration offset is initially determined that accounts for the errors caused by antenna and signal interfaces. Further refinement is performed by accounting for errors caused by the frequency margin between the main and accessory signals.