The Research On Metrology Of Pulsed Electromagnetic Fields

Electromagnetic Pulses(EMP)are widespread in natural world and modern life.Accurate EMP measurement technology is of great significance in electronic countermeasures,power system operation and microwave communication.The nanosecond EMP detection system should have a large bandwidth,a fast response time,and a flat frequency response.However,due to the slow response time,traditional electric field probe lacks the ability to capture transient EMP.For the metrology of pulsed electromagnetic fields,the National Institute of Metrology and Standardization(NIST)and the Korea Metrology Institute(KRISS)have established corresponding national metrology standards.Tsinghua University,Northwest Institute of Nuclear Technology and other institutions have carried out some research on the metrology methods of pulsed electromagnetic fields.Regrettably,China has not yet established a metrology standard for pulsed electromagnetic fields,so measurement equipment with different performance cannot be accurately calibrated.The metrology of pulsed electromagnetic field mainly includes two basic problems:the generation of standard pulsed electromagnetic field and its accuracy verification.Based on this background,this paper focuses on the following aspects:Firstly,analysis on conical antenna electromagnetic-radiation characteristics is carried out in obedience to the basic theory of time-varying electromagnetic field.Accuracy of calculatable standard EMP generator using conical antenna is obtained via theoretical calculation and modelling simulation.Combined with the simulation results,optimized designs concerning model size and input impedance are made and relevant bases are laid for single cone-plate system modelling.Secondly,by means of equivalent circuit model,D-dot EMP sensor measurement principle and impedance characteristics are theoretically explored.The impedance matching of the D-dot electric field probe and transmission line are realized by utilizing the negative impedance transformation characteristics of the non-Foster circuit in simulation software,and the corresponding optimized model studies the response time and frequency response flatness of improved D-dot EMP sensor.Lastly,measurement on single cone-plate system is carried out with accurately calibrated SBA-9113 conical antenna,and feasibility of actual single cone-plate system is verified.In the facet of data processing,time-domain antenna factor is adopted to describe transient receiving characteristics of antenna under test.Thesis central results are as follows.The key issues of generating standard pulsed electromagnetic field with conical antenna are mastered through theoretical analysis.Single cone-plate system can function as a standard pulsed electromagnetic field generating device.Considering factors such as impedance matching,signal strength and test space,the optimized device construction parameters are set as 32° half cone angle and 2.1 m height.The D-dot sensor matched by non-Foster circuit can conspicuously improve the receiving sensitivity in measuring weak pulsed electromagnetic field,and has good frequency response flatness in the frequency range of 700MHz-2.3GHz,which is expected to be used in accurate verification of standard pulsed electromagnetic field.In the frequency range of 300MHz-3GHz,the average error between the preliminary measurement result and the theoretical calculation of the mirror single cone system is 1.68dB.The time-domain antenna factor contains all the information of commonly used antenna factor,and can also visually characterize the response time characteristics of measured sensor.This measurement results are of reference value for future research on metrology technology of EMP involving time-domain antenna factor.