Agilent Technologies 4395A - Page 431

Calibration
for
Network
Measurement
Figure
A
-38.
Load
Match
E
LF
The
measured
value
,
S
21M
,
consists
of
signal
components
that
vary
as
a
function
of
the
relationship
between
E
SF
and
S
11A
as
well
as
ELF
and
S
22A
,
so
the
input
and
output
reection
coecients
of
the
test
device
must
be
measured
and
stored
for
use
in
the
S
21A
error
correction
computation.
Thus
,
the
test
setup
is
calibrated
as
described
above
for
the
reection
to
establish
the
directivity
,
E
DF
,
source
match,
E
SF
,
and
reection
frequency
response
,
E
RF
,
terms
for
the
reection
measurements
.
Now
,
that
a
calibrated
port
is
available for
reection measurements
,
the
THRU
is
connected
and
load
match,
E
LF
,
is
determined
by
measuring
the
reection
coecient of
the THRU
connection.
Transmission
signal
path
frequency
response
is
then
measured
with
the THRU
connected.
The
data
is
corrected
for
source
and
load
match
eects
,then
stored
as
transmission
frequency
response
,
E
TF
.
Isolation
Errors
.
Isolation, E
XF
,
represents
the
part of
the
incident
signal
that
appears
at
the
receiver
without
actually
passing through
the
test
device
(
Figure
A
-39
).
Isolation
is
measured
with
the
test
set in
the transmission
conguration
and
with
terminations
installed
at
the
points
where
the
test
device will
be connected.
Figure A
-39. Isolation E
XF
Error T
erms the 4395A Can Reduce
. Thus there are two sets of error terms
, forward and
reverse, with each set consisting of six error terms
, as follows:
Forward
Directivity,E
DF
Isolation, E
XF
Source Match, E
SF
Load Match, E
LF
Transmission Tracking, E
TF
Basic Measurement Theory A-55