Power Level Accuracy

(N5161A / N5162A / N5166B / N5171B / N5172B / N5181A / N5181B / N5182A / N5182B / N5182N)

Power level accuracy is the difference between the power level indicated by the device under test (PDUT), and the true power delivered by the DUT (PgZ0).

PLAdB = PgZ0 - PDUT

Direct absolute power measurements are made with a power meter for the higher powers. For lower powers, a cross-calibration is performed and remaining powers measured with the spectrum analyzer.

Required Test Equipment

Test Equipment

Recommended Model

Alternate Models

Power Meter

N1914A1

E4419A/B
E4418A/B
N1911A/12A/13A

Spectrum Analyzer

N9030B Opt 5xx3, MPB, Pxx4

E444xA2 Opt 110 and 123
E444xA2 Opt 1DS, 123
E444xA2 Opt 1DS
E444xA2 Opt 110
E444xA2 Opt 123
E444xA2

N9030A Opt 5xx3, MPB, Pxx4
N9030A/B Opt 5xx3, MPB
N9030A/B Opt 5xx3, Pxx4
N9030A/B Opt 5xx3

Power Sensor

E9304A
use with standard model DUTs

E9304A Opt H19
use with Opt 1EA DUTs or standard model DUTs

N8482A

N8482A CFT
use with standard model DUTs

E9304A H18

U8481A5 Opt 200
U8485A5 Opt 200
  1. Power meter N1914A with serial numbers ranging between MY00000000—MY53040007 require Service Note N1914A-07 to be applied for measurement repeatability. Please have this service note applied or verify it was applied before using this power meter. The affected service note is N1914A-07.
  2. Select any model of PSA spectrum analyzer (E4440A, E4443A,E4445A, E4446A, E4447A, E4448A) that has a maximum frequency greater than or equal to the maximum frequency of the unit under test. The E4448A frequency range is adequate for all DUT frequency configurations.
  3. Select any option of PXA spectrum analyzer (503, 508, 513, 526, 543, 544, 550) that has a maximum frequency greater than or equal to the maximum frequency of the unit under test. The N9030A/B Option 550 frequency range is adequate for all DUT frequency configurations.
  4. Select any preamplifier option for the PXA spectrum analyzer (P03, P08, P13, P26, P43, P50) that has a maximum frequency greater than or equal to the maximum frequency of the unit under test. The N9030A/B Option P50 frequency range is adequate for all DUT frequency configurations.
  5. Requires power meter N1914A with USB ports. Refer to the main Required Equipment table for more information.

Connections and Setup Procedures
  • All test equipment requires a 30 minute warmup period to ensure accurate performance.
  • In the following test setup, cables are designated as solid lines and direct connections are designated as dashed lines.
  • At low power levels, residual spurs from adjacent instruments can cause the UUT to fail the test. Therefore, the instruments must be adequately separated from one another. Do not place one device on top of another. If the test fails at very low power levels, offset all frequencies by +25 Hz or -25 Hz and manually verify. This will shift the test frequency away from possible residual responses.
  1. Connect all test equipment as shown.
  2. Connect GPIB cables to all GPIB-controlled test equipment.
  3. While performing this test, follow all instructions on the controller display.

Flexible power sensor channel assignment

This test uses flexible power sensor channel assignment and will identify the channel that a power sensor is connected to using the ability of "smart" sensors such as the N848xA, U848xA, and E930xA series to report their full model and serial number.

Select from the links below for connection setups depending on the power sensor.

ClosedSetup using standard power sensors

 

ClosedSetup using USB power sensors

 

In Case of Difficulty

  1. Sometimes noise from nearby test equipment can affect low-level measurements. Errors may be caused even if the power meter is stacked on top of the spectrum analyzer.

  2. Inspect all RF cables. If semi-rigid cables are used, check for cracks in the shielding or at the connectors. RF leakage to/from the cables generally cause problems at higher frequencies (> 2 GHz) and low power levels (< -100 dBm).

  3. Verify that the spectrum analyzer does not have a residual spur at the frequency being measured. Sometimes a spur will limit how low in power the spectrum analyzer can measure.

  4. Make sure that all test equipment is using the same power outlet. Ground loops can cause problems at low power levels. This type of problem will most likely show up at lower frequencies.

  5. Make sure all covers on the DUT are secure and that all screws are in place.

  6. Make sure all connections in the measurement system are torqued properly. Loose or damaged connections result in RF leakage and errors result at low power levels.

  7. Make sure all test equipment has been turned on at least 30 minutes.