vector network analyzer 8 the rf signal can include a scan over a desired range of frequencies the response of the uut 2 is measured on port 2 of vector network analyzer 8 for each position over the azimuth elevation range the response is detected as output voltage from the antenna or device containing the antenna which is then converted by the analyzer to power which is related to the gain of the antenna the data is converted to calibrated gain 13 and stored by the pc controller 10 the calibrated gain data 13 over the specified azimuth elevation range forms the basis for the gain probability function computation 12 described herein for a cellular phone network the polarization is assumed to be vertical however scattering from nearby objects as well as ground reflections result in polarization diversity the present invention can characterize both vertical and total gain to account for performance variations due to multi path effects additionally the present invention allows a much more robust basis for antenna comparison than simply peak or average gain since the ordered statistical method of the present invention is impervious to deep nulls which can bias average gain measurements additionally the present invention provides a method to predict.