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Precision power measurement
In this method, power is calculated using differential voltages (V
obtained by measuring V
multimeters. This method helps to reduce measurement error to
± (0.2%+0.5 μW).
To use this method, first you need to perform zeroing of the N432A and
measure its V
These V
will obtain V
need to connect RF power to the thermistor sensor and measure the V
and V
V
can then be computed by incorporating these values in the following
power equation:
where,
• V
• V
• V
• V
• R is the bridge resistance
• ε is the correction factor/effective efficiency
N432A User's Guide
and V
RF
and V
RF
COMP
which is the difference between V
0
outputs again. These V
COMP
and V
, which will give you a differential voltage of V
RF1
COMP1
=
P
is the temperature compensation bridge top voltage measured
COMP0
when zeroing is performed with the RF source disconnected
is the temperature compensation bridge top voltage measured
COMP1
after zeroing with the RF source connected
= V
– V
0
COMP0
RF0
= V
– V
1
COMP1
RF1
and V
outputs with external digital
RF
COMP
outputs using external digital multimeters.
COMP
are equivalent to V
and V
RF
(
–
2 V
V
V
COMP1
1
COMP0
-----------------------------------------------------------------------------------------------------
4Rε
, without incident RF power
, with incident RF power
Operating Information
and V
. From this, you
RF0
COMP0
and V
COMP0
RF0
are now equivalent to
COMP
) V
2
–
2
V
+
V
0
0
1
2
and V
)
0
1
. Then, you
RF
. Power
1
79
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