Agilent Technologies Option H48 Multiport Test Set Z5623A - Manual (Page 74)

5 -6 Agilent Technologies Z5623A Option H48
Performance Verification
Test Strategy
Return loss is specified for two different conditions:
• Test port active (this means that the test port is internally connected
either to the Reflection port or to the Transmission port)
• Test port off (this means that the test port is internally connected to
a 50-ohm termination)
Return loss is specified for the test ports, but not for the Reflection and
Transmission ports.
Crosstalk
This measurement will be performed between each of the test set’s
pairs of adjacent test ports (1 and 2, 2 and 3, 3 and 4, etc.). The test set
will be commanded to connect its Reflection port to one of the test ports
in the pair, and to connect its Transmission port to the other test port in
the pair. An RF cable will connect Port 1 of the network analyzer to the
Reflection port of the test set. Another RF cable will connect Port 2 of
the network analyzer to the Transmission port of the test set. Network
analyzer calibration will be turned off for this measurement. (The
reason is that the isolation calibration achievable with the Electronic
Calibration module is not good enough.) A Type N 50-ohm male short
will be mounted on each test port in the pair.
The network analyzer will be configured to measure S
21
. By definition,
Crosstalk = S
21
for the setup described above. Limit lines will be set up in such a way
that each S
21
limit equals the corresponding crosstalk test limit shown
in Table 5-2 .
Crosstalk is a maximum spec. Therefore, each S
21
limit will be set up as
a maximum limit. For example, if a crosstalk test limit happens to be
−100 dB, the corresponding S
21
limit will be set up so that S
21
must be
below −100 dB in order for the instrument to pass.