Rohde & Schwarz URV5-Z4 - Page 41

3.4.2.2
Checking
the
Reflection
Coefficient
Linearity
and
reflection
coefficient
are
characteristic
data
of
the
1oo-v
insertion
unit.
If
both
are
within
the
Specifications,
the
frequency
response
will
also
be
within
the
specified
toleran-
ces.
Measurement
of
the
reflection
coefficient
of
the
100-V
insertion
unit
is
slightly
critical,
since
3%
is
not
exceeded
over
the
en-
tire frequency range. The measurement must therefore be carried
out
particularly
carefully.
The
test
set
used
should
have
a
di-
rectivity
of
at
least
46
dB.
The
measurement
level
is
uncritical.
since it has practically no influence on the reflection coeffi-
cient. The insertion unit to be tested is terminated at one end
by
50
n
for
low
reflection;
for
the
measurement
result
it
is
ir—
relevant
whether
the
insertion
unit
is
connected
to
the
basic
unit
or
not.
Care
should
be
taken
that
the
reflection
coefficient
of
the
so-n
termination
does
not
exceed
0.5%.
The
permissible
reflection
coefficient
tolerances
for
the
100-V
insertion
unit
are
specified
for
100
MHz
to
2
682
in
the
perform-
ance
test
report.
These
tolerances
do
however
295
include
the
measurement
error
of
the
test
set
used.
Please
check
first
what
reflection
coefficients
you
can
still
measure
with
sufficient
ac-
curacy.
The
following
example
should
prove
to
be
helpful.
A
test
set
with
a
directivity
of
46
dB
yields
already
an
uncertainty
of
10.5%.
Together
with
the
reflection
coefficient
of
the
termi-
nation
of
0.5%,
the
entire
test
set
has
a
measurement
error
of
21%.
Therefore,
only
reflection
coefficients
>
3%
can
reliably
be
determined.
Consequently,
the
reflection
coefficient
of
the
100-V
insertion
unit
can
only
be
checked
for
frequencies
above
1
GHz.
A
test
set
for
measuring
the
reflection
coefficient
up
to
2
GHz
and
with
a
directivity
of
46
dB
is
described
in
section
3.8.
It
contains
the
R&S
VSWR
Bridge
ZRBZ
and
a
URVS
with
two
RF
probes.
394.8010.02
3.21
3-2
3.4.2.2
Checkinq the
Reflection Coefficient
Linearity and reflection
coefficient are
characteristic
dat.a
of
the 100-v
Insertion Unit. If both are mithin the sgecificatıons,
the frequency response will also be weithin the specified toleran-
ces.
Measurement of the reflection coefficient of the 100-V inser ton
Unit is slightly Critical, since 3% is not exceeded Over the en-
tire frequency range. The measurement must therefore be carried
out par
ticularly carefully. The test Set used should have a di-
rectivity of at least 46 dB. The measurement level is uncritical.
since it has practically no influence on the reflection coeffi-
cient. The Insertion Unit to be tested is terminated at one end
by S0 n for los reflection; for the measurement result it is ir-
relevant whether the Insertion Unit is connected to the basic
Unit er not. Care should be taken that the reflection coefficient
of the
so-n
termination does not exceed 0.5%.
The permissible reflection coefficient tolerances for the 100-V
Insertion Unit are specified for 100 MHz to 2 GHz in the perform-
ance test repor t. These tolerances do however not include the
measurement error of the test Set used. Please Check first what
reflection coefficients you can still measure Voith sufficient ac-
curacy. The following example should prove to be helpful. A test
Set Voith a directivity of 46 dB yields already an
uncer tainty of
±O.5%. Together Voith the reflection coefficient of the termi-
nation of 0.5%, the entiretest Set has a measurement
error of
±1%.
Therefore, only reflection coefficients › 3% can reliably
be
determined. Consequently, the reflection coefficient of the 100-V
iser ton Unit can only be checked for frequencies
above 1 GHz.
A Test Set for measuring the reflection coefficient up to 2 GHz
and Voith a directivity of 46 dB is described in section 3.8. It
container the R&S VSWR Bridge ZRB2 and a URV5 Voith toto RF probes.
394.8010.02
3.21 E-2