Millimeter-wave Linear Fm Radar System Analysis And The Vco Design

In this paper, the engineering and technological research of MMW (millimeter wave) radar detection system is presented, and the principle of LFMCW (Linear frequency modulated continuous wave) radar system is discussed. This paper analyzes the performance specification of the radar system, calculates the radar system's errors, and accomplishes the index distribution. Based on the principle of electromagnetic theory and circuit analysis, this paper analyzes the two ports negative resistance oscillating network and the equivalent circuit model of the parallel varactor tuned oscillator. The circuit model of the longitudinal configuration of the varactor and Gunn diode, along the waveguide cavity, is used to design the VCO. Its main cavity uses the height reduced waveguide, and DC biasing circuit uses the structure of coaxial lowpass filter. The paper determines the distance between two device and length of the waveguide cavity. A circuit for open loop linearization of electronic tuning characteristic of VCO is designed. Experimental results indicate that the electronic tuned bandwidth is more than 300MHz, the tuning nonlinearity is less than 2% and the output power is no less than 50mW. The Gunn diode varactor tuned oscillator possesses good stability and high reliability, small size: 29 × 16 × 16mm, and is convenient in processing. The good behavior of the spectrum is also observed. A T/R front-end at Ka-band is carried out by the VCO with applicable circulator and mixer. The experimental results are agreed with the theoretic results, indicating that the scheme demonstration and performance evaluation of the LFMCW radar system are completed correctly. It is of great value to the subsequent development of MMW radar.