Agilent Technologies 4395A - Page 429

Calibration
for
Network
Measurement
Figure
A
-34.
Open
Circuit
T
ermination
Now
the
unknown
is
measured
to
obtain
a
value
for
the
measured
response
,
S
11M
,
at
each
frequency
(
Figure
A
-35
).
Figure
A
-35.
Measured
S
11
This
is
the
one-port
error
model
equation
solved
for
S
11A
.
Because
the
three
errors
and
S
11M
are
now
known
for
each
test
frequency
,
S
11A
can
be
computed
as
follows:
S
11
A
=
S
11
M
0
E
D
F
E
S
F
(
S
11
M
0
E
D
F
)
+
E
R
F
F
or
reection
measurements
on
two-port
devices,
the same
technique can
be applied,
but
the
test
device
output
port
must
be
terminated
in
the
system characteristic
impedance
.
This
termination should be at least as good (have as low a reection coecient) as the LO
AD used to
determine directivity
. The additional reection error caused by an improper termination at the
test device output port is not incorporated into one-port error model.
Basic Measurement Theory A-53