A Research Of K-band Radar Front-End Technology

Since the military and civilian integration strategy was put forward,the comprehensive promotion of military and civilian integration in various fields has become the general trend of future development.Therefore,radar technology,as a traditional military technology,will also be greatly developed in the civilian field.The main purpose of this paper is to develop a K-band radar front-end suitable for short-range detection,the main research focuses on the realization of low cost,miniaturization,low power consumption and high integration of the radar front-end,so that it can meet the immediate needs of the civilian areas such as vehicle radars,unmanned aircraft obstacle avoidance systems and artificial intelligence.This paper introduces the basic theory of radar front-end and analyzes the radar operating characteristics of different systems,combining with the demand characteristics of the application of the short-range radar,a radar operating system based on the linear frequency modulated continuous wave(LFMCW)is proposed,and plans the overall implementation of the front-end system.In order to realize the requirement of the front-end system to the cost and power consumption,the design of the active circuit in the system adopts the low cost and low power consumption FET to develop and realize.In order to realize the miniaturization and integration of the front-end circuit,this paper adopts the scheme of multi-layer circuit through the vertical interlayer interconnection.In this paper,the active circuits developed by FET.First of all,this paper developed a harmonic voltage-controlled oscillator circuit and a VCO linearization circuit based on phase-locked technology,the fundamental output frequency of the harmonic VCO is 11.9~12GHz,and the fundamental frequency is used for linearization calibration circuit for the PLL feedback input signal.The harmonic frequency is 23.8~24GHz,it is the output frequency of VCO in the radar system.Due to the poor linearity of the free-running VCO affecting the performance of the LFMCW radar,therefore,this paper developed a linearization calibration system based on PLL.Followed by the K-band amplifier and the active mixer research,amplifier uses two cascaded ways to achieve system gain up to 21 dB of demand.The active mixer adopts the method of drain mixing to realize the high isolation between RF and local oscillator,and the mixer can produce 1dB conversion gain if LO input maximum power.For the passive circuit development of the system,including filters,couplers,inter-layer interconnect structure and microstrip array antenna.This paper focuses on the microstrip array antenna and the interlayer interconnect structure,the transceiver antennas achieve up to 20 dB of gain with 32(8 × 4)and 48(8 × 6)array elements,respectively,besides,the wide receiving range of the receiving antenna and the high resolution of the transmitting antenna are respectively realized.Finally,after the completion of the development of the unit circuit to achieve the system integration of the front-end,the system integration mainly includes the integration of RF circuits,the vertical interconnection between the microstrip array antenna and the RF circuit layer,and the integration of the space structure of the RF part and the power supply and signal processing part.After the integration of the transceiver link passed the test experiment,respectively.Based on the above design ideas,finally,a circuit design method based on the combination of self-oscillation mixing and phase-locking technology was adopted to further enhance the low-cost,low-power and miniaturization integration radar front-end systems further,at last,the feasibility of this scheme is verified through experiments.