8 Mm Frequency Modulation Continuous Wave Short-range Detection System Design

This paper is about the design of eight millimeter frequency modulation continuous wave (LFMCW) close detection system and its realization.First of all, this thesis introduced the operating theory of the LFMCW detection system, followed by design targets of8mm LFMCW close detection system. Then, it analysed the model of target in the air detected by conical-pattern radiation antenna and the signal to noise ratio and the best explosion time based on antenna alike.By the result of the model estimation, the conical-pattern radiation antenna and its excitation of the detection system are designed, the main lobe of the antenna is on55°of its direction, by8.66dB, and the fifty percent of power is on61.2°and41.2°of it. The side lobe is6.07dB below the main lobe with2.59dB. Coaxial waveguide convert to rectangular waveguide is excited by probe, which is chosen for this antenna. The excitation’s standing-wave ratio is1.03on34GHz.Meanwhile, according to the indexes of system, modulated signal generator of triangular wave is made; The VCO of eight millimeter is designed by the use of rectangular waveguide cavity; some circuits and devices are designed to strengthen different frequency signals, including a passive BPF with the structure of LC and a intermediate-frequency amplifier made up with EL2020as the core chip. The hardware and software of digital signal processing system are realized by F2812. The design of hardware part is mainly on the initialization of important hardwares and functions of its perpherals. The design of hardware part is mainly on the initialization of ADC by program and the processing algorithm of different frequency signals are introduced.