HP 8753D - Page 346

Each
standard must
be identied
as one
of
ve
\types":
open,
short,
load,
delay/thru,
or
arbitrary
impedance.
After
a standard
number
is
entered,
selection
of
the
standard
type
will
present
one
of ve
menus
for entering
the
electrical
characteristics
(model
coecients)
corresponding
to
that
standard type
, such
as
NN
NN
NN
NN
NN
NN
N
N
OPEN .
These menus
are tailored
to the
current type
,
so
that
only
characteristics
applicable
to
the
standard
type
can
be
modied.
The
following
is
a
description
of
the
softkeys
located
within
the dene
standard menu:
N
N
N
N
N
N
N
N
N
N
N
NN
N
OPEN
denes
the
standard
type
as
an
open,
used
for calibrating
reection measurements
.
Opens are
assigned
a
terminal
impedance
of
innite
ohms
,
but
delay
and
loss
osets
may
still be
added.
Pressing
this
key
also
brings
up
a
menu
for
dening
the
open,
including
its
capacitance
.
As
a
reection
standard,
an
open
termination
oers
the
advantage
of
broadband
frequency
coverage
.
At
microwave
frequencies
,
however
,
an
open
rarely
has
perfect
reection
characteristics
because
fringing
capacitance
eects
cause
phase
shift
that
varies
with
frequency
.
This
can
be
observed
in
measuring
an
open
termination
after
calibration,
when
an
arc
in
the
lower
right
circumference
of
the
Smith
chart
indicates
capacitive
reactance
.
These
eects
are
impossible
to
eliminate
,
but
the
calibration
kit
models
include
the
open
termination capacitance
at
all
frequencies
for
compatible
calibration
kits
.
The
capacitance
model is
a cubic
polynomial,
as
a
function
of
frequency
,
where
the
polynomial
coecients
are user-denable
. The
capacitance
model
equation
is:
C
=
(C0)
+
(C1
2
F)
+
(C2
2
F
2
)
+
(C3
2
F
3
)
where
F
is
the
measurement
frequency
.
The
terms
in
the
equation
are
dened
with
the
specify
open
menu
as
follows:
N
N
N
N
N
N
N
N
C0
allows
you
to
enter
the
C0
term,
which
is
the
constant
term
of
the
cubic
polynomial
and
is
scaled
by
10
0
15
F
arads
.
N
N
N
N
N
N
N
N
C1
allows
you
to
enter
the
C1
term,
expressed
in
F/Hz
(F
arads/Hz)
and
scaled
by
10
0
27
.
N
N
N
N
N
N
N
N
C2
allows
you
to enter
the C2
term,
expressed
in
F/Hz
2
and
scaled
by
10
0
36
.
N
N
NN
NN
N
N
C3
allows
you
to
enter
the
C3
term,
expressed
in
F/Hz
3
and
scaled
by
10
0 45
.
N
N
N
N
N
N
N
N
NN
NN
NN
N
N
N
SHORT
denes
the
standard
type as
a short,
for calibrating
reection measurements
.
Shorts
are
assigned a
terminal
impedance
of
0
ohms
,
but
delay
and
loss
osets
may
still
be
added.
N
N
N
N
N
N
N
N
N
N
N
N
NN
LOAD
denes
the
standard
type
as
aload
(termination).
Loads
are
assigned
a
terminal
impedance equal to the system characteristic impedance Z0, but delay and loss osets
may still be added. If the load impedance is not Z0, use the arbitrary impedance standard
denition.
NNNNNNNNNN
NNNNNNN
FIXED denes
the load as a xed (not sliding) load.
NNNN
NNNNNNNNNNNNNNNNNNN
SLIDING denes the load as a sliding load. When such a load is measured during
calibration, the analyzer will prompt for several load positions
, and calculate the ideal load
value from it.
NNNNNNNNNNNNNNNNNNNN
OFFSET denes the load as being oset.
N
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
DELAY/THRU denes the standard type as a transmission line of specied length, for
calibrating transmission measurements.
Application and Operation Concepts 6-79