The Research Of Doppler Sensor Based On Miniaturized Antenna

With the rise of the internet of things, sensors have been developing very quickly,especially the growing demand of microwave doppler sensor, which mainly used inautomatic induction door for business premises, housing intrusion alarm device, thebank teller smart video, underground parking auto-sensing, traffic speed, automotiveanti-collision. The microwave doppler sensor with the doppler Effect can detect theposition, the moving speed and direction of the object. Unlike the passive infrareddetector, it can radiate electromagnetic wave, and when the electromagnetic wavesreflect back by the target, detailed information of the target can be obtained from theecho signals. The front end circuit of the doppler sensor affects the overall performanceof the system. This paper attempts to improve the traditional doppler sensor, proceedfrom the oscillator, mixer, antenna, and strive to meet the performance indicators as wellas the volume decreases.The dielectric resonator oscillator and SIW-CSRR microstrip bandpass resonatoroscillator are designed. The both oscillators are compared, and high output power, lowphase noise are achieved in the DRO; SIW-CSRR microstrip bandpass resonatoroscillator resonator is proposed for the first time, and its volume is relatively small.In the design process of the mixer, the pros and cons of the traditionalsingle-balanced structure are analyzed. The performance of inverting and phase shift of90°balanced mixer structure performance is good, but the volume is relatively large.According to the requirements of the subject, a U-shaped structure is used in the mixerusing a single balanced structure, whose diodes is inputted across by the LO signal andthe RF signal, and this structure under conditions that satisfy performance largelyreduces the size.In the design process of the antenna, the traditional rectangular microstrip antennastructure is improved. The CSRR structure loaded in the rectangular microstrip antennaground, the antenna size is reduced by34.53%, while the performance of the antennaunchanged. This paper firstly describes the doppler sensor theory as well as oscillator, mixerand antenna theory. Electromagnetic simulation software HFSS and circuit simulationsoftware ADS are used to simulate and optimize them.