Frequency Source Design And Implementation For FMCW Angle-measuring Radar System

Millimeter wave band is 26.5GHz-300 GHz.The millimeter-wave system is easier to miniaturize because the wavelength is short.Millimeter wave technology is the key technology to solve the shortage of spectrum resources and has great significance in the field of communications and radar,especially in the field of automotive crash radar.Although Millimeter wave linear frequency modulation continuous wave(FMCW)radar has a broad market and social significance,it is facing many challenges such as high product cost,hard to popularize,technical blockade.The working frequency of the FMCW radar in this thesis is 75.9GHz-76.5GHz.It has advantages of high measurement precision,low transmission power,low product cost and simple transmission waveform and can be used in automotive anti-collision,security detection,UAV detection and other fields by using different detection algorithms.In this thesis,relied on FMCW angle measuring radar project,the Ku-band FMCW frequency source covering 12.65GHz-12.75 GHz is designed by comparing the advantages and disadvantages of different schemes.The structure of the frequency source is the mixing of the PLL in the phase-locked loop(PLL)and the mixing of the DDS outside the ring.The output signal of the frequency source is multiplied by six times and then as output signal of the radar system.In order to improve the purity of the spectrum,a novel filter is proposed.This filter using half mode substrate integrated waveguide(HMSIW)and defected ground structure(DGS)is highly selective.The main contents of this thesis are as follows:(1)The present situation of FMCW radar and frequency source at home and abroad are Summarized.The basic principle of FMCW radar is introduced.(2)Main technology of modern frequency synthesizer are introduced.Optimal scheme base on project requirments is determined by comparing the advantages and disadvantages of various frequency source schemes.Then,feasibility and performance of the proposed scheme is analyzed.(3)A DGS mixed Half-Mode SIW filter is proposed.The filter has high selectivity,low insertion loss and can be used in this design.(4)The hardware and software of the frequency source according to the scheme are designed.the test results are given and it meets the project requirements.Finally,the radar test results are given.