Methods and apparatus for correction of cable variations

Methods and apparatus are described for automatically determining correction factors for an electrical device to compensate for variations in the device as a result of mechanical and/or environmental influences, using a "three cable" method. A primary cable is used to conduct signals between electrical devices, for example a probe antenna and an antenna under test ("AUT") in an antenna test range. The primary cable is subjected to mechanical and/or environmental influences such as cable flexing and temperature changes. A first secondary cable and a second secondary cable are provided alongside the primary cable, and are subjected to similar environmental influences. A switching network connects the primary cable, the first secondary cable, and the second secondary cable in combinations to form three cable pairs during a calibration mode. A computing system determines insertion factors associated with the primary cable at a first time and a second time, using transfer functions associated with the cable pairs. A correction factor is determined using the insertion factors associated with the primary cable at the first time and the second time. The correction factor is applied to data transmitted via the primary cable during use of the primary cable in an antenna measurement mode, to compensate or adjust for the mechanical and/or environmental influences upon the primary cable.