Making a Basic Average Power Measurement

To make an average power measurement, you connect the power sensor and cable, zero and calibrate the meter, and then take a reading.
 When should you zero the Power Meter?
 When should you calibrate the Power Meter? Every time you cycle the power on and off.
 To Make a Basic Average Power Measurement:

Step
 		Notes
1
 		Mode
2
 		[Power Meter]
3
 		[Zero]
 		Follow the Zeroing Wizard, which displays instructions on the screen.
4
 		[Continue]
5
 		[Ref CF]
6
 		Enter the reference cal factor using the numeric keypad.
The reference cal factor is printed on the label of the power sensor head.
7
 		[%]
8
 		[Calibrate]
9
 		Connect the power sensor to the Power Ref 50 MHz port.
 		The test set supports the Agilent 8482A and 8481A power sensors.
10
 		[Continue]
11
 		[Cal Factor]
12
 		Enter the cal factor using the numeric keypad.
A list of cal factors is printed on the label of the power sensor head. Select one that's within the operating frequency of the base station.
For an example of a power sensor calibration table, see below.
 Using the example power sensor calibration table, if you were interested in 800 MHz, then:
800 MHz has a Cal Factor percentage of ~98.2
Note: Interpolate the Cal Factor from the frequency range provided on the power sensor. The example sensor calibration table shows that 800 MHz is between 300 to 1000 MHz. Since 300 MHz is listed at 98.5 and 1000 MHz (1 GHz) is at 98.1, 800 MHz would be ~98.2.
13
 		[%]
14
 		Connect the external attenuator.
15
 		If you have previously stored PM loss from an insertion loss measurement, go to the next step.

Or

Press [PM Loss] and enter the PM loss value.
 		For information on the effects of the PM Loss function on the measurement, refer to "Using the Power Meter Loss field, below.
16
 		Connect to the base station.
Connect the power sensor to the signal to be measured. The connection is typically after the output of the power amplifier or duplexer. The connection requires, in addition to the power sensor and attenuator, a 2 ft. cable and two Type-N barrel connectors.

Using the Power Meter Loss Field

Typical base stations exceed the maximum input to most power sensor heads. Therefore an attenuator (typically a 40 dB 100 W attenuator) is required. The measured value of the attenuator and connecting cables is entered into this field. This value is then used when this field is set to On. When this field is set to On, the test set will add this loss value to the true measured value indicating the displayed measured value.
Example: The base station transmits 40 dBm (10 W), the attenuator and RF cabling measures 42.51 dB (measured with the 2 port insertion loss measurement prior to this test), and the PM loss is turned On (with the 42.51 dB loss value entered). The true measured level (using an 8481A sensor) is -2.51 dBm (the attenuator and RF cabling attenuated the signal to within the proper range for the sensor), but the displayed measured value is 40 dBm (10 W), which is correct. This also points out the importance of accurately measuring the loss of the attenuator and connecting cables.

Using the Power Ref Button to Verify the Sensor Is Working Properly

With the sensor head connected to the Power Ref 50 MHz RF Port and selecting Power Ref to On, you can verify that the sensor is working correctly. In this configuration, the power meter should indicate approximately 0 dBm (1 mW) as it reads the 50 MHz, 0 dBm RF signal.
 Example of a Sensor Calibration Table (Agilent 8482A)
MHz
CF%
.1000
97.3
.3000
99.0
1.0
99.0
3.0
99.0
10.0
99.5
30.0
99.1
100
98.8
300
98.5
1000
98.1
2000
97.4
3000
98.1
4000
90.5