HP 8753D - Page 293

S-Parameters
The
4
MEAS
5
key provides
access to
the
S-parameter
menu
which
contains
softkeys
that
can
be
used
to select
the parameters
or
inputs
that
dene
the
type
of
measurement
being
performed.
Understanding
S-P
arameters
S-parameters
(scattering
parameters)
are
a
convention
used
to
characterize
the way
a device
modies
signal
ow
.
A
brief
explanation
of
the
S-parameters of
a two-port
device is
provided
here
.
F
or
additional
details
refer
to
Hewlett-P
ackard Application
Notes A/N
95-1 and
A/N
154.
S-parameters
are
always
a
ratio
of two
complex (magnitude
and phase)
quantities
.
S-parameter
notation
identies
these
quantities
using
the numbering
convention:
S
out
in
where
the
rst
number
(out)
refers to
the test-device
port where
the signal
is
emerging
and
the
second number
(in) is
the test-device
port where
the
signal
is
incident.
F
or
example
,
the
S-parameter
S
21
identies
the
measurement
as the
complex ratio
of
the
signal
emerging
at
the
test
device's
port
2
to
the
signal
incident
at
the test
device's
port
1.
Figure
6-8 is
a
representation
of
the
S-parameters
of
a
two-port
device
,
together
with
an
equivalent
owgraph. In
the illustration,
\a"
represents
the
signal
entering
the
device
and
\b"
represents
the
signal
emerging.
Note
that
a
and
b
are
not
related
to
the
A and
B input
ports on
the
analyzer
.
Figure 6-8. S-Parameters of a Two-Port Device
6-26 Application and Operation Concepts