Research On Angle Measurement Accuracy And Gain Flatness Of Magnetic Loop Antenna Used For Lightning Direction Finding

Lightning is a natural phenomenon that occurs frequently,which is often accompanied by strong currents,high voltages and radiating electromagnetic pulses.According to statistics,nearly2,000 lightning strikes occur every second in various regions of the world.Thunder and lightning will cause serious interference to human survival and production.Therefore,it is of great significance to carry out research on lightning detection and provide accurate lightning positioning and prediction.This paper analyzes and studies the structural characteristics of the Orthogonal Magnetic Loop Antenna(OMLA)for lightning detection,improves its structure,and proposes a new structure of direction-finding antenna.It is proved by MATLAB simulation and actual measurement that the angle measurement accuracy of the three-magnetic loop antenna under the same structural error can be improved by about 50%.In order to improve the signal detection effect of the magnetic loop antenna,a method to determine the coil parameters and gain flatness of the magnetic loop antenna is proposed,which provides a theoretical basis for the optimal design of the magnetic loop antenna.The research content is as follows:(1)First,Introduces the research background and significance of lightning direction finding magnetic loop antenna technology,with emphasis on the development process and development status of related technologies at home and abroad.(2)Introduces the direction finding principle of the lightning direction finding magnetic loop antenna.According to the system composition,it is divided into single-station and multi-station lightning direction finding antennas.The corresponding direction finding methods of the two systems are introduced respectively,and their advantages and The disadvantages were compared and analyzed.Furthermore,the possible errors in OMLA direction finding are analyzed,including polarization error,site error and antenna structure error,and correction methods are given respectively.Finally,the dynamic receiving characteristics of orthogonal magnetic loop antennas are discussed,including frequency response,receiving bandwidth and gain flatness.These characteristics reflect the ability of the antenna to receive signals and have an important influence on the accuracy of the antenna's direction finding.(3)Analyzing the influence of traditional OMLA's own structure on the direction finding accuracy and improving its structure,a new type of lightning direction finding antenna is proposed.It can improve the accuracy of direction finding.First,the structural characteristics of the new antenna are introduced,and the formula for calculating the direction angle under low frequency conditions(f<400KHz)is given.A simulation model of the angle measurement error with respect to the structural error angle is constructed in the MATLAB environment.The simulation results show that under the same structural error condition,the angle measurement error of the three-magnetic loop antenna can be reduced by about 50%.Furthermore,a near-field magnetic field was set up in the laboratory to conduct an angle measurement comparison test on the OMLA made with the same magnetic loop and the three-magnetic loop antenna.The test results show that the angle measurement accuracy of the three-magnetic loop antenna is improved by about 50%,and the test results are in good agreement with the simulation.(4)The dynamic receiving characteristics that affect the direction finding accuracy of the magnetic loop antenna mainly include bandwidth,frequency response and gain flatness.Past studies have proved that by increasing the antenna size and increasing the number of turns,the performance of the magnetic loop antenna can be improved.Frequency response value,but there are relatively few studies on the flatness of antenna reception gain.This chapter studies the frequency response curves of orthogonal magnetic loop antennas of different sizes and turns when detecting magnetic field signals,and analyzes the influence of different design parameters on the flatness of antenna spectral gain.Aiming at the central frequency band of lightning electromagnetic pulse from 10 KHz to 400 KHz,one is proposed.A design method to determine the optimal gain flatness of magnetic loop antennas of different sizes in the lightning center frequency band of the coil turns,size and matching resistance is of certain significance for improving antenna detection accuracy.