On the measurement of power via a superheterodyne spectrum analyzer

The measurement of power via a superheterodyne spectrum analyzer is investigated. In particular, the performances of two common measurement techniques, in which one is based on a “channel-power” approach and the other on the use of the analyzer in a “zero-span” mode, are assessed. The purpose is both to show advantages and drawbacks of these techniques and to provide useful hints for improving the measurement accuracy and repeatability. To this aim, an original theoretical approach, which is suitably supported by meaningful experimental examples, is proposed in this paper. The experiments also show how to compensate some typical measurement errors due to the analyzer video-filter effects by a simple calibration procedure.