The Research On Coupling Characteristics Of Mast Of Ships And Non-uniform Twisted Wires Pair Under Nuclear Electromagnetic Pulse Environment

Modern ships often face the threat of the strong electromagnetic pulse environment.The nuclear electromagnetic pulse environment is an important category of strong electromagnetic pulse environment.The strong electromagnetic pulse environment can couple energy into the interior of the electronic device through "front door coupling" or "back door coupling".The "back door coupling" can be divided into hole coupling and transmission line coupling.In order to better predict the electromagnetic coupling characteristics of the ship under the nuclear electromagnetic pulse environment,this paper selects the typical structure of the ship and the twisted wires pair as the research object,based on the time domain finite integration method and the transmission line analysis method to quantify the electromagnetic coupling characteristics.Furthermore,considering the inhomogeneity of the twisted wires pair in reality,the non-uniformity factor is introduced to establish the coupling model of the non-uniform twisted wires pair under the nuclear electromagnetic pulse environment.Through numerical analysis and experimental verification,it provides guidance for the design of typical structures of ships.The main research results of this paper are as follows:(1)Based on the time domain finite integration method,the coupling characteristics of the typical mast structure of the ship under nuclear electromagnetic pulse environment are studied.Four different models of mast structure were established.The electromagnetic coupling characteristics of the mast under different polarization modes and different incident angles were studied in detail.The electromagnetic coupling characteristics of the metal-made mast is compared with the composite mast;(2)The time domain coupling model of twisted wires pair under nuclear electromagnetic pulse environment is proposed,the software calculation module is written.the terminal coupling characteristics of the twisted wires pair under the nuclear electromagnetic pulse environment is studied.The study found that the smaller the torque,the smaller the coupling power;the total length does not affect the envelope of the coupled power curve,the total length will affect the distribution of the resonance point,and the coupled power curve exhibits significant resonance characteristics.The peak of the coupled power appears at an odd multiple of the half-frequency point corresponding to the total length,and the coupling valley point appears at an integer multiple of the corresponding frequency of the total length;(3)The time-domain coupling model of the non-uniform twisted wires pair under the nuclear electromagnetic pulse environment is proposed by introducing the non-uniformity factor,and the influence of the non-uniformity of the twisted wires pair on the coupling characteristics is studied.It is found that for the case where the total length is equal,the number of twists is equal,but the size of each torque is not equal,in the frequency domain,the non-uniformity makes the resonance point distribution of the coupling curve not obvious,and the resonance characteristics are weakened.In the time domain,non-uniformity will cause fluctuations in current peaks.The range of fluctuations will increase as the non-uniformity factor increases.In other words,an increase in the non-uniformity factor will increase the probability that the current peak exceeds the expected value;(4)The coupling characteristics of the typical shipstructure with twisted wires pair are studied.The influence of the metal-film coated on the window of view on the shielding characteristics is studied in detail.The study found that the longer the length of the twisted wires pair exposed to the outside of the cockpit,the greater the terminal coupling voltage of the twisted wires pair,and the larger the electric field peak in the cockpit;Coating the metal film can effectively improve the shielding performance of the cockpit.