A-10 Service Guide E8361-90001
Error Terms PNA Series Microwave Network Analyzers
Error Term Data E8361A
Directivity (E
DF
and E
DR
)
E
DF
and E
DR
are the uncorrected forward and reverse directivity error terms of the system.
The directivity error of the test port is determined by measuring the S
11
and S
22
reflection
of the calibration kit load. The load has a much better return loss specification than does
the uncorrected test port. Therefore, any power detected from this measurement is
assumed to be from directivity error.
The measurements most affected by directivity errors are measurements of low reflection
devices.
Typical Cause of Failure
The calibration kit load is the most common cause of directivity specification failure.
If the load has been gaged and its performance independently verified, suspect the
analyzer test port coupler.
To troubleshoot, refer to “Checking the Signal Separation Group” on page 4-49.
Figure A-3 Typical E
DF
/E
DR
Without Cables
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