Meaning
Radio frequency measurements verify the output power of a wireless device before it enters the antenna matching network. An RF connector on the device board provides a conductive power sample to the test equipment for transmission verification. This measurement defines the baseline transmitter performance of the device without the influence of the antenna pattern.
Lab testing requires this reference to ensure that the device does not exceed maximum rated limits during conducted emissions tests.
Measurement Setup
Physical cables establish a direct signal path between the device under test and the power meter. To obtain a valid conductive power sample, a coaxial pigtail is soldered to the board or a dedicated RF switch connector is used. The attenuator in the line prevents overloading the sensitive receiver of the power meter.
This configuration isolates the transmitter behavior from any over-the-air loss.
Calibration Factor
The path loss of the measurement cable must be calibrated across the entire operating frequency band. When analyzing a conductive power sample, the software applies these frequency-dependent correction values to report the absolute power. This step ensures that the logged transmission levels match the actual power at the output pin of the chipset.
Failure to account for cable losses leads to false failures or misleading compliance margins during regulatory filings.
System Integration
Compliance protocols use these conducted levels to scale specific absorption rate results. By comparing the over-the-air measurements with the conducted power sample, engineers verify the radiation efficiency of the integrated antenna structure.
