X-band Doppler Velocimetry Receiver Key Technologies

Not only in civil but also in military field,Doppler velocity-measuring system is beingstudied and used widely. Nowadays we use it to measure velocity and guide planes tosafely land in cloudy and blizzard days.It is not only used to search and detect the enemy'splane, naval vessel and vehicle, but also used to act as weapon guidance,and so on.Atmospheric attenuation for X waveband is small.So the design and research for the Xwaveband Doppler velocity-measuring receiver is very important.This thesis studies some critical devices of X band Doppler velocity-measuringreceive front-end and signal processing circuits. There are five chapters in this thesis.The first chapter initiates simply this subject background, meaning, domestic andoversea development and the main work.Chapter 2 initiates some base theory about Doppler velocity-measuring. Then, thechief scheme of the receiver is presented.Subsequently, the auther analysis the key receiverparameters using ADS and specific devices' index distribute of receive front-end, which isthe basis of the later research and design.Chapter 3 introduces the principle theory of line polarization microstrip antenna,Coupled-Line Bandpass Filter, Low Noise Amplifier and mixer of X waveband.And theauther gives the designs of them using ADS,the LNA and the mixer MMICs' trendsnowadays.In the fourth chapter, the traditional methods of increasing the dynamic range of thereceiver are analyzed.And an Automatic Gain Control circuit is designed and simulated.In the fifth chapter, an active filter, a plastic module and a digital frequency counterare designed and simulated on count of the whole performance of the system.In the end of the thesis, the anther gives some improvement advise and easily ignoredpoints, which will be useful to the further research on the work.