Uncertainties in NIST noises-temperature measurements
J. Randa · 1998
Uncertainty analyses are presented for NIST measurements of noise temperature.All systems currently used in NIST calibrations of thermal-noise sources are treated.These include tuned systems for 30 and 60 MHz, coaxial total-power radiometers for 1 to 12 GHz, a switching radiometer for the WR-90 (8.2 to 12.4 GHz) waveguide band, and total power waveguide radiometers for the WR-62 (12.4 to 18 GHz), WR-42 (18 to 26.5 GHz), WR-28 (26.5 to 40 GHz), and WR-15 (50 to 75 GHz) bands.Measurements through adapters are also analyzed.Typical expanded {k = 2) uncertainties for the measurements are in the range 0.7 percent to 1.4 percent, depending on the particular system and the frequency.