Etalons primaires de bruit thermi-que sur guide d'ondes entre 8,2 GHz et 40 GHz

摘要

The national metrology laboratory, BNM-LCIE, has developped, during the last few years, four new waveguide primary thermal noise standards for frequencies between 8.2 GHz and 40 GHz. Each noise standard is made with silicon carbide microwave absorber and inserted into a section of waveguide which is built in platinum 10 % rho-dium,the whole is put inside an electrical oven. The excess noise ratio calculated by making teperature measurements is within 3.5-4.0 dB and the typical uncertainty is estimated at 0.01dB.The calibration of gas discharge noise sources or solid state noise sources is achieved by comparison with standards using a switching radiometer. The excess noise ratio obtained is within 15.35-15.65 dBfor gas discharge sources and within 14-16 dB for solid state sources, with typical uncertainty of 0.02 dB.