The concept of the receiver cal is to take a known source power at some source reference plane and transfer that knowledge to the receiver at a desired receiver reference plane. If it is convenient to use the test port as the source reference place, the built-in factory ALC calibration can be used to establish the power knowledge. If this is not convenient (because of frequency translation or some other network is required, or greater accuracy is needed), then a power calibration can be performed with the help of a GPIB-controlled power meter to better establish that power knowledge. Power calibrations are covered in more detail in the Sweep Types portion of this Measurement Guide and in the Operation Manual.

In all of these discussions, power refers to signal amplitude at the fundamental frequency. Since the receivers are all tuned they are not measuring full integrated power as in a power meter. This can be important as will be discussed in the uncertainties section.

The receiver calibration menu system begins under the Power menu (since it is associated with power reference planes rather than S-parameter calibration). The Receiver Setup menu is shown in Figure: RECEIVER SETUP Menu.

 

There are four different receiver calibrations possible (since there are four receivers in the MS4640A Series VNAs) and they can be activated at the top of this menu. A menu item will be active only if that calibration exists. The calibrations can be saved and recalled from this menu. Calibrations can also be saved and recalled as part of the global setup save using the commands located under the FILE menu.