HP 8508A - Page 41

g
Operation
b. Reflection
The
measurement
of
small
reflections
in
high
frequency
RF
systems
requires
careful.consideration.
At
low
levels,
reflections
from
the
device
under
test
can
be
masked
by
leakage
signals
in
the
measuring
equipment,
so
to
make
the
measurement
accurately,
you
will
need
to
use
a
high
directivity
reflection
bridge
or
directional
coupler.
Use
a
short
circuit
as
a
calibration
standard,
and
measure
the
return
loss
of
a
precision
termination.
_~
Source
:
HP8508A
50echm 500hm
"A Input "B* Input
{| Short circuit
Device Under
Test
Directional Bridge
Figure 3-12. Bridge Test Setup
Source
HP8508A
500hm
"B" Input
50 ohm
“A’ input
Incident
+]
Short
circuit
Device Under
Test
Directional Coupler
Figure 3-13. Coupler Test Setup
3-17