Technical data

Service Guide N5230-90025 8-11
PNA Series Microwave Network Analyzers General Purpose Maintenance Procedures
N5230C Error Terms
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 4-38.
Source Match (E
SF
and E
SR
)
E
SF
and E
SR
are the forward and reverse uncorrected source match terms of the driven port. They are
obtained by measuring the reflection (S
11
, S
22
) of an open, and a short that are connected directly to the
ports. Source match is a measure of the match of the coupler, as well as the match between all components
from the source to the output port.
The measurements most affected by source match errors are reflection and transmission measurements of
highly reflective DUTs.
Typical Cause of Failure The calibration kit open or short is the most common cause of source match
specification failure.
If the open or short performance has been independently verified, then suspect the analyzer switch splitter,
step attenuator, or coupler.
To troubleshoot, refer to “Checking the Signal Separation Group” on page 4-38.
Load Match (E
LF
and E
LR
)
Load match is a measure of the impedance match of the test port that terminates the output of a 2-port
device. The match of test port cables is included in this response. Load match error terms are characterized
by measuring the S
11
and S
22
responses of a “thru” configuration during the calibration procedure.
The measurements most affected by load match errors are all transmission measurements, and reflection
measurements of a low insertion loss two-port device, such as an airline.
Typical Cause of Failure The calibration kit load or a bad “thru” cable is the most common cause of load
match specification failure.
If the load and cable performance are independently verified, then suspect the analyzer test port coupler,
step attenuator, or the test receiver at the bad port.
To troubleshoot, refer to “Checking the Receiver Group” on page 4-42 or to “Checking the Signal Separation
Group” on page 4-38.