Accuracy considerations in the measurement of the power gain of a large microwave antenna

Accuracy considerations in the measurement of the power gain of a large microwave antenna are discussed. The analysis indicates that, using the power gain comparison method with a standard antenna of nominally 40-dB gain, a large antenna with a power gain of nominally 60 dB could be calibrated to within an error of 0.17 dB (3\sigma). The power gain of the standard antenna is considered to be determined via the generalized three-antenna extrapolation method. Individual sources of errors in both the generalized three-antenna extrapolation method and the power gain comparison method are discussed.