It has been proven that calibrating at 10 mW is typically high enough above the sensor's noise floor to be considered in the linear region. The specification for the Agilent 8481B (0 to 44 dBm) states a negligible linearity deviation up to +30 dBm, meaning the sensor’s response should be no different at 10 dBm than at 20 dBm.
The data provided below shows an 8481B calibrated at both 10mW and 100mW.
The System IIB is fully capable of measuring both the 8481B and 8482B power sensors as well as a wide variety of other sensors. The central component of the System IIB is the 1806A Dual Type IV Power Meter. This along with transfer standard such as the F1130A and SureCAL software, most sensors in the 100 kHz to 18 GHz range can be calibrated in less than 5 minutes. Some important things to consider when calibrating at 10 mW.