Power sensor linearity calibration with an unknown attenuator

This paper describes the linearity calibration of power sensors using the setup for the direct comparison method. To achieve sufficient dynamic range an attenuator is used. The S-parameters of the attenuator need not be known because the effective attenuation can be calculated from two sets of measurements on the device under test. This way the linearity is traced to a monitoring power sensor instead of the S-parameters of the attenuator. The method is verified with a bilateral comparison.