Research On Variable Temperature Noise Source Of Three Millimeter Wave Band

With the further development of the three millimeter wave in modern communication and military fields,the key technology of three millimeter wave band is becoming more and more important.The three millimeter wave band has great advantages in many fields of the industry,together with the development and layout of the modern communication network.Based on the above points,there is a growing demand for accurate measurement technology of small noise covering the three millimeter wave.The measurement uncertainty of small noise coefficient is high,and the frequency range of three millimeter wave should be covered by frequency conversion.Therefore,this paper studies the noise measurement device of three millimeter wave band,and focuses on the development of the noise source which can provide high measurement precision in the three millimeter frequency band.The noise source is also known as the noise generating device.It's main function is to output a certain noise power to the input part of the tested devices.In general,the noise source is divided into two types: active and passive.The three millimeter wave noise source studied in this paper is a passive noise source based on the variable temperature noise source method.The range of temperature variation is 70K-300 K and the frequency range is 90GHz-100 GHz.The main principle of measurement is as follows.With the temperature controlled by a variable temperature platform,the noise source can output several sets of different noise temperatures to the input ports of the tested devices.Then,the output noise power corresponding to the equivalent noise temperature of the previous noise sources is obtained through the relevant detection instruments at the output ports of the tested devices.During the subsequent data processing,the equivalent noise temperature of the measured piece can be calculated because of the linear correspondence between the equivalent noise temperature and the actual measured noise power.The main work of the three millimeter wave frequency band noise source includes the manufacture the hardware part of the noise source and the calibration of the noise source's equivalent output noise temperature.The hardware manufacture is the research and design of variable temperature load,adiabatic transmission waveguide,sealed window and low noise amplifier.Through theoretical argumentation,emulation software simulation and optimization,the specifications and sizes can be determined and used to process physical objects.In the software aspect,the data about the temperature distribution and the output noise power are obtained by experiments and the corresponding data are arranged to complete the calibration of the equivalent output noise temperature equation of the noise source.Using the noise source to detect the small noise figure of the W band waveguide connector,and compare it with the vector network analyzer.Finally,repeatability experiments are conducted to verify the performance and reliability of the developed noise source system.