Meaning
Ratios between the incident electric field strength and the resulting voltage at the antenna terminal establish the core calibration metrics for radiated emissions testing. When a lab carries out radiated emissions scans, antenna factors must be added to the raw receiver readings to determine the true field strength. These values are specific to each frequency and are provided in a manufacturer calibration table.
Mathematical Ratio
Conversion of measured voltage to field strength requires a precise log scale addition. Engineers use antenna factors expressed in decibels per meter to adjust the raw spectrum analyzer values. The calibration process defines the exact transfer function of the antenna.
Without this conversion, the data collected during tests remains uncorrected for the specific physical dimensions and gain of the transducer.
Calibration Value
Traceability to a national standards body ensures the reliability of these measurement factors. These factors are typically renewed annually by a certified laboratory to account for physical wear or drift.
Testing Procedure
Radiated emission limits are defined by international standards such as CISPR 32. In the test setup, the technician loads the antenna factors into the automation software. Modern software applies these factors dynamically as the receiver sweeps through the designated frequency band.
If the wrong table is used, the system may register a false pass or an unnecessary failure. Therefore, the serial number of the active transducer must match the active calibration file.
