Study On Microwave And Millimeterwave Radar Frequency Synthesizer

With the development of radar technology, the task of a radar is expanded to measuring not only the distance, direction and elevation angle of the target, but also the speed, and other essential information of the target from the echo signals in order to identify objects. The Radar frequency synthesizer is one of the key components of a radar system, since it provides not only the local oscillator and reference signal to the radar receiver, but also the transmitter excitation signal and system clock to the coherent radar. It is therefore important and necessary to study the frequency synthesizer.This dissertation focuses on the design and performance of the high performance microwaves and millimeter-wave radar frequency synthesizers, and examines the technology of frequency synthesizers and its application in four aspects:1. This study proposes a novel wideband agile frequency synthesizer with lowphase noise and high spurious suppression. Combining DDS, PLL and FPGAcan solve the problems caused by low operation frequency of DDS and longfrequency conversion time of PLL. In the study, a wideband agile frequencysynthesizer working at C-band is developed. The bandwidth of the synthesizeris 1.016 GHz with a 8MHz step size, the phase noise is lower than-102dBc/Hz@10kHz and the spur suppression is better than 55 dBc, and thefrequency convertion time is less than 0.5μs.2. This study proposes a design for the coherent interpulse stepped-frequencyradar transceiver front-end frequency synthesizer. By making the full use ofthe advantages of various kinds of frequency synthesizers and optimizing thefrequency configuration, the problems of coherent and isolation between theoutput signals are solved.3. This study provides theoretical basis and engineering reference for designingLFM radar frequency synthesizer with high performance. In order tounderstand the effects of various parameters on the signal linearity, somesimulations are carried out by using the formulas derived from the analysis oflinear frequency modulated(LFM) signal under the influences of constantphase difference, single frequency modulation and Gaussian noise, separately.4. Last but not least, this dissertation shows that the digitization of radarwaveform can be achieved by using DDS. However, it can not be applied to the millimeter-wave radar directly due to its low operation frequency. To solve the problem, this study proposes a design for the millimeter-wave radar frequency synthesizer based on existing frequency synthesizers and verifies its feasibility with experiments.