Analysis Of HEMP Coupling Characteristics Based On Transmission Line Theory

Electronic equipment is widely used in the national defense as well as the people's daily life.Malfunction of some key equipment may affect the entire industry,even can be a threat to the national security as a result.The HEMP has strong electromagnetic interference capabilities.The wide-spectrum and high-intensity electromagnetic pulse radiated by highaltitude explosion at 100 km can damage the unprotected electronic system within the radius of 1100 km,especially incompletely shielded transmission and antenna which are used to transmit signals.Therefore,it is necessary to study front-door coupling characteristics of HEMP.This paper focus on EMP simulator using for HEMP radiation sensitivity test and the response between HEMP and structures such as transmission line and antenna.Transmission line is considered as the main part in this paper,also studied the farend crosstalk under injection and irradiation circumstances.The following work has been carried out:1.According to the theory of transmission line,the response of lumped excitation source in time domain and frequency domain is analyzed.The FDTD method is used in time domain,the BLT equation and chain parameter equation are used in frequency domain.The time domain crosstalk response of non parallel transmission lines is simulated by FDTD method,while the crosstalk response of lossy ground transmission lines is solved by frequency domain method.2.The effect of HEMP on two coupling path that are antenna coupling and transmission line coupling is studied respectively.In dealing with the coupling problem of antenna,a discrete grid whip antenna model is established by FDTD method,and the induced electric field values of sampling points in the antenna coaxial connector under different incident angles are simulated.Aiming at the field line coupling problem of HEMP as plane wave incident,the distributed excitation source model of transmission line is established,and the influence of incident angle,polarization direction and transmission line length on load response is analyzed respectively.3.The EMP simulator of the EMP radiation sensitivity test is studied.This model of bounded-wave simulator is built which consists of two overhead cables and ideal ground plane.After injecting pulse source into two wires,the wire is equivalent to dipole antenna to radiate electromagnetic field outward.The radiation field in half space is simulated in computer by TDIE algorithm,and different test positions are recorded.The rise edge and half wave width of the electric field waveform are compared with HEMP standard time domain waveform to verify the feasibility of the model.