The 8484A High Sensitivity Power Sensor measures power from 0.1nW to 10 W over a frequency range of 10MHz to 18GHz. It is furnished with the 11708A 50MHz reference attenuator for precise calibration with 1 mW power meter reference oscillator. Noise and drift have been reduced to less than 5% of full scale on the 300 pW range (only 15 pW) when it is used with the 435B power meter. Noise and drift are even less with the 436A, 437B and 438A power meters.