Boonton 9240 RF Voltmeter - Manual (Page 50)

Boonton 9240 Series RF Voltmeter
Figure 3-4. Correction Curves for Models 952003 and 952007 Type N tee Adapters.
4.11 RF Power Measurements
The Z
0
function in the CHANNELS sub-menu enables the user to set a characteristic impedance to be used for power
calculations. The default value is 50 ohms; however, values from 5 to 2500 ohms may be used. This value is used only in
association with the dBm and dBW units. The power level is calculated using the expression:
P = V 2 /Z
0
where V is in volts
Z
0
is in ohms
P is in watts
For dBm units, the result is the ratio in decibels of the calculated power to 1 milliwatt (0 dBm = 1 milliwatt). For dBW units,
the result is the ratio in decibels of the calculated power to 1 watt (0 dBW = 1 watt). This capability is useful for determining
the power dissipated in a nonstandard load impedance or in a load which is not part of a coaxial transmission line. The
accuracy of this method depends upon the ability to measure the effective voltage across the load. The RF Probe enables the
user to reach components mounted on circuit boards.
Operation
4-4