Research On The Key Technology Of Ultra Wideband Radar Sensor With Small Size

Ultra-wideband(UWB)radar has strong penetrating power on walls,leaf clusters and other obstructions,so it has the ability to detect targets hidden behind walls or foliage clusters.And UWB radar can also avoid multipath interference during communication.What's more,it is not affected by rain or snow,sound or wind and other natural environment interference so it will work all day no matter what the weather is.Therefore,UWB radar has been widely used in the field of target detection and communication.In this paper,we focus on micro-UWB radar which can be used as distance detecting sensor of wireless sensor network.The UWB can also be used as a communication device in urban wireless sensor networks.This paper focuses on core technologies of micro-UWB radar sensor——narrow pulse circuit,microstrip antenna and sampling gate circuit.The paper studies its theory and experiment,designs the relevant circuit and microstrip antenna,and carries on the simulation verification.The specific research results are as follows:1.A narrow pulse generation circuit is designed.For the application of the micro-UWB radar sensor,the narrow pulse width should be 0.4ns~1ns,the amplitude should be as high as possible,and the waveform of the narrow pulse should be bipolar.According to the step effect of the step recovery diode,a narrow pulse generation circuit with step recovery diode as the core device is proposed and simulated.The simulation results show that the width of the bipolar narrow pulse is 700 ps and the pulse amplitude is ± 1.26 V.2.A novel microstrip antenna with small structure is designed.According to the theory of microstrip antenna and coplanar waveguide,the working bandwidth of the antenna is widened by loading the resonant structure on the microstrip antenna.Moreover,the proposed antenna has symmetrical structure design to achieve better omnidirectional.A printed slot antenna fed by coplanar waveguide is proposed,and its performance is analyzed in detail by means of simulation verification.The results show that the working bandwidth of this antenna is 1.78GHz~2.38 GHz,which meets the requirements of design and ultra-wideband.In addition,the designed antenna has a good omnidirectional.3.The sampling gate circuit and symmetrical sampling pulse circuit were designed.According to the principle of distance detecting and the design requirements of the sampling gate,design a bridge sampling gate circuit using four Schottky diodes.But the bridge sampling gate circuit needs two positive and negative sampling pulses as trigger switches,so we have to design symmetrical sampling pulse circuit which is combinded with recovery diode and microwave triode.Moreover,we study the performance of sampling gate circuit and symmetrical sampling pulse circuit in detail through a series of simulation and verification.The results show that there are two unipolar pulses with good symmetry,and the pulse width is 300 ps.What's more,the sampling gate circuit has the function of signal reproduction and distance detecting.The three technologies studied in this paper are the key technologies of micro-UWB radar sensor.And it provides a theoretical basis for the development of micro-UWB radar sensor.