Rohde & Schwarz URV5-Z4 - Page 45

3.5.2.;
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
5%
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
75
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
75-9
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
report.
These
tolerances
do
however
225
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
tO.S%.
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.
394.301o.oz
3.25
3-2
3.5.2.2
Checking the Reflection
Goefficient
Linearíty
are
and
reflection' coefficient characteristic 'data of
tue 100-V Insertion Unit. If both
are weithin the sgecifications,
the frequency response will also be weithin the specified
toleran-
ces.
Measurement of the reflection coefficient of the 100-V Insertion
Unit is slightly Critical, since 5% 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 75 n for low
reflection; for the measurement result it is ir-
relevant whether the inser tion Unit is connected to the basic
Unit er not. Care should be taken that the reflection coefficient
of the 75-Q 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 Report. 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 uncertainty of
±O.5%. Together Voith the reflection coefficient of the termi-
nation of 0.5%, the entire test Set has a measurement
error of
±1%.
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.
394.8010.02
3.25
E-2