The Development Of W-Band Noise Source

Due to the short wave length,excellent anti-jamming ability,sufficient bandwidth capacity and other advantages,millimeter wave is widely used in the field of vehicle-mounted collision avoidance radar,large capacity communication,space satellite com-munication and so on.At present,spectrum resources of W band attracting the attention of researchors increasingly.Moreover,one of the key indicator of an microwave,mil-limeterwave receiving system is noise factor,decided the quality of the receiving system.However,the accuracy of noise factor measurement depends basically on the noise source.Unfortunately,at present,W-band noise sources mostly rely on foreign products,and the price is extremely expensive.Therefore,this thesis will study W-band noise sources.The main content of this thesis is divided into the following parts.Firstly,Development of noise sources.Most active devices are assembled on planar circuits,but for millimeter wave circuit systems,the signal through the waveguide can achieve better low-loss transmission.Therefore,it is significantly to Design and simulate a transition structure that microstrip transmission line convert to waveguide with better performance.Design and manufacture a constant current source circuit to provide a stable output working current for the noise diode,to ensure that the noise diode is in a reverse avalanche breakdown state,and generated a large amount of relatively flat Gaussian white noise.The low-pass filter is designed to play the RF choke effect of the feed circuit and avoid the leakage of noise power from the feed end.The parameters of the noise diode are extracted,the S parameter of the noise diode is measured by de-embedding,and the characteristic impedance of the noise diode is obtained and verified by simulation fitting.Impedance matching is performed on the obtained characteristic impedance,so that the noise diode can output the maximum noise power,thereby increasing the Excess noise ratio and improving the standing wave.Secondly,select a spectrum analyzer as a receiving device to build a noise power receiving platform,and at the same time make a noise amplification module to ensure that the noise power can be detected by the receiving platform.First of all,the noise floor of the spectrum analyzer is higher than the standard thermal noise,and the noise power generated by the noise source is still more difficult to detect for the spectrum analyzer.Therefore,it is necessary to design and manufacture a W-band noise power amplifier module to increase the noise power so that it can be detected by the noise power receiving device.At the same time,considering the high local frequency of the variable frequency equipment de-veloped by the laboratory,the cavity filter is designed to avoid the risk of other influence errors caused by the interference of the image frequency during the measurement process,thereby reducing the influence of other uncertainties.Finally,study the noise measurement method,and carry out the Excess noise ratio calibration of the noise source.Under the existing conditions in the laboratory,the gain method is used for noise power measurement and calibration.Subsequently,the noise source of the preliminary calibration is measured and verified,the error is corrected,and a more accurate Excess noise ratio is obtained,and then the uncertainty analysis is carried out.After measuring the Excess noise ratio of noise source by gain measurement method and correcting the error,an active solid-state noise source with Excess noise ratio higher than 10dB and flatness ± 1.8dB in the 88GHz-96GHz frequency band is finally realized,which initially meets the design and use requirements.