Research On Measurement Technology Of Millimeter Wave Noise Coefficient

To a large extent,the progress of engineering has been always depended on the development and progress of test equipment.As the frequency extends in the direction of high frequencies,the measurement of noise figure has become more and more difficult.However,noise,which cannot be ignored in microwave communication design,is difficult to measure accurately by the instrument when its value is tiny.However,the noise measurement manufacturers usually base their products on solid-state noise sources,whose uncertainty is too large to measure extremely low noise figures;instead,it is based on the addition of liquid nitrogen and boiling water.Though there are measurement system,which using standard noise sources of hot and cold noise,has enjoyed a better degree of uncertainty,it requires two sets of noise sources,which is very inconvenient.Therefore,this project studies a millimeter-wave noise figure test system to measure millimeter-wave noise figure in a more efficient and accurate way.This paper first introduced the related theory of noise and noise testing,and then proposed the index and principle of the millimeter-wave noise testing system.Through the theoretical analysis and ADS simulation design or selection,the millimeter-wave amplifiers,mixers,IF amplifiers,and IF filters has been designed and the millimeterwave noise figure test system has been successfully constructed.Using this noise figure test system,a millimeter wave low noise amplifier has been measured.The noise temperature of the millimeter-wave DUT was calculated to be 721.26 K.Then this paper has discussed the uncertainty and repeatability of the noise test system and them analyzed the source of uncertainty and the contribution of each part uncertainty source to the total uncertainty.The analysis concludes that besides the uncertainty contributed by the noise source and the measurement instrument,the largest uncertainty contribution of the system came from the link inconsistency of the hardware.After analysis and calculation,the noise coefficient measurement system's uncertainty is better than 10%,and the measurement result is relatively stable.It means the millimeter-wave noise figure test system can be used to test millimeter-wave devices or systems.This paper has also provided some suggestions for improving the uncertainty of the noise figure test system.