HP 8753D - Page 305

Scale Reference
Menu
The
4
SCALE
REF
5
key provides
access to
the
scale
reference
menu.
Softkeys
within
this
menu
can
be used
to dene
the
scale
in
which
measured
data
is
to
be
displayed,
as
well
as
simulate
phase
oset and
electrical delay
.
The
following
softkeys
are
located
within
the
scale
reference
menu.
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NN
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AUTO
SCALE
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NN
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SCALE/DIV
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REFERENCE
POSITION
NN
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REFERENCE VALUE
NN
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N
MARKER !
REFERENCE
N
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NN
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NN
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N
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N
ELECTRICAL
DELAY
N
N
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N
N
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NN
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PHASE
OFFSET
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NN
COAXIAL
DELAY
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WAVEGUIDE
DELAY
Electrical
Delay
The
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NN
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NN
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N
ELECTRICAL
DELAY
softkey
adjusts
the
electrical
delay
to
balance
the
phase
of
the
test
device
.
This
softkey
must
be
used
in
conjunction
with
N
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NN
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NN
N
COAXIAL
DELAY
or
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NN
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WAVEGUIDE
DELAY
(with cut-o
frequency)
in
order
to
identify
which
type
of
transmission
line
the
delay
is
being
added to
.
Electrical delay
simulates a
variable
length
lossless
transmission
line
,
which
can
be
added
to
or
removed
from
a
receiver
input
to
compensate
for
interconnecting
cables
,
etc
.
This
function
is
similar
to
the
mechanical
or
analog
\line
stretchers"
of
other
network
analyzers
.
Delay
is
annotated
in
units
of
time
with
secondary
labeling
in
distance
for
the
current
velocity
factor
.
With this
feature,
and with
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N
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MARKER !
DELAY (see
\Using Markers"),
an
equivalent
length
of
air-lled,
lossless
transmission
line
is
added
or
subtracted
according
to
the
following
formula:
Leng
th (
meter
s
)
=

( Freq
( MHz
) 2 1 :
20083)
Once the linear portion of the test device's phase has
been removed, the equivalent length of
the lossless
, transmission line can be read out in
the active marker area. If the average relative
permittivity (
"
r
) of the test device is known over the frequency span, the length calculation can
be adjusted to indicate the actual length of the test device more closely
. This can be done by
entering the relative velocity factor for the test device using the calibrate more menu. The
relative velocity factor for a given dielectric can be calculated by:
V elocity F actor =
1
p
"
r
assuming a relative permeability of 1.
6-38 Application and Operation Concepts