Electronic Calibration Modules Reference Guide         3-7
Operating ECal Module
Setting Up a Calibration
When to Correct for Isolation 
Correction for isolation is a consideration when measuring high-loss devices 
such as saw filters or diplexers. When maximum dynamic range is required, 
correction for isolation can remove the errors due to crosstalk (between test 
ports) for transmission measurements.
When you include isolation with a two, three, or four-port calibration, the 
analyzer automatically applies averaging to reduce noise in the measurement. 
Without averaging, you will have noise in the measurement of the crosstalk, 
and could raise the noise floor when the analyzer uses this in its error 
correction. 
The analyzer system isolation is normally sufficient for most measurements, 
and correction for it is usually unnecessary. As long as crosstalk is below the 
noise floor, it is best NOT to correct for isolation using ECal. As of PNA firmware 
release 4.26, measuring isolation as part of the ECal process is no longer 
supported.