Abstract：The 18～26.5 GHz power density standard system developed at the National Institute of Metrology of China is presented,with the stress on the improvements in the system, compared to the existing 1～18 GHz one, which include the determinations of the horn gain and the net power, the suppression of harmonics, and the performance improvement and the validation of the site.The reliability of the system is verified by measuring the site voltage standing wave ratio and probe linearity. The comparison with the 1～18 GHz system shows that the two systems agree well at 18 GHz, which indicates the accuracy of the 18～26.5 GHz system. A preliminary evaluation of the uncertainty of calibrations is also presented, and the expanded uncertainty is 0.48 dB(k=2).
［2］IEEE Std 1309—2005, IEEE Standard for Calibration of Electromagnetic Field Sensors and Probes, Excluding Antennas, From 9 kHz to 40 GHz ［S］.
［3］Newell A, Baird R, Wacker P. Accurate measurement of antenna gain and polarization at reduced distances by an extrapolation technique ［J］.IEEE Transactions on Antennas and Propagation,1973, 21(4): 418-431.
2015, Vol. 36 
