| As electronic technology is developing toward high frequency, high-speed, high sensitivity, high reliability, multi-function and miniaturization, electromagnetic interference modern electronic equipment increases rapidly. Electromagnetic compatibility(EMC) means the coexistent state of various electro or electric systems, that every electronic equipment can function normally. EMC is an important quality specification for electronic equipment, which ensures the system working efficiently and improves the reliability of the system. Electromagnetic compatibility had drawn much great attention from industry, research institutions and military departments, becoming international mandatory standard in electronic product, having taken by many countries. In problems of electromagnetic compatibility shielding is thought as one of the three major resolution means, attracted much concern from researchers.Two major coupling ways are "back door" coupling and "front door" coupling. Study on coupling is a key problem to research on systematic effect and strengthen system technology under strong electromagnetic environment.By theoretical and numerical analysis, this thesis studies the coupling between strong electromagnetic pulse of the external environment and aperture in empty cavity, cavity with printed circuit board and metal support separately. The higher the voltage of electric wire and the more the underground pipelines, the more serious the interference between the underground electric power line and the underground pipeline. The dissertation analyses the mutual inductance coefficient between the underground electric power line and the underground pipeline and deduced the formula on shielding effective. The major research results are as the following:1. The Robinson, M.P basic theories of transmitting line model has been introduced to calculate the shielding efficiency of rectangle with holes. The polarized direction of electromagnetic pulse was not considered in Robinson, M.P basic theories. In this dissertation, analysis including the polarized direction of electromagnetic pulse is carried out. The results of the analytic calculation and numerical analysis on various conditions are discussed, such as the size, shape, position of the hole, the distance between holes, the polarized direction of the electromagnetic pulse et al. Conclusions of the strengthening technique in shielding are obtained.2. The loss property of the electromagnetic waves relies on materialsurface, based on this conclusion, and the energy of electric field coupled into the body is concentrated in the adjacent resonance frequency, and endangers the electronic system in the shielding, the best restrain result of resonance frequency under the electrolyte thickness have been realized by adjusting coating the lossing artificial electrolyte aiming at the resonance frequency in the cavity.3. The shielding is designed to protect the electronic system; the dissertation uses the electric magnetic field theory to analyze the shielding. The shielding coefficient formulae of the cavity with printed circuit are brought forward, the result from the formula and numerical calculation agrees well. The loss function of the circuit board can obviously improve the shielding efficiency around the resonance frequency of the body. The energy in the resonance frequency body has strongest influence on the printed circuit board.4. The metal sheet or metal support is usually installed in the shielding.Electromagnetic theory for wave guide is used to analyze and deduce shielding coefficient formulae of the shielding with metal sheeting or metal support. The calculation result from the formula and the numerical emulation agrees well. The factor, such as metal size, metal position, number of metal sheet, et al, can remarkably change the resonance frequency. Because the electric field energy coupled into the body concentrates on the adjacent resonance frequency, it is very important in theory and practice when design a cavity to protect the electronic system effectively from the electromagnetic pulse. But the metal plate in cavity can not change the whole shielding coefficient in the body.5. Interference between underground strong electric power line and the ground pipeline is getting more and more serious, the existing calculative formula to solve the mutual inductance coefficient between two underground cables is treated by calculation of infinite integral with special function. This dissertation has deduced the mutual inductance coefficient between underground strong electric wire and underground pipeline with special function being expanded and properly trunked, the simplified calculation formula is obtained as formula of reduction does not contain special function and complicated infinite integral, which has been proved under the extreme condition, it is suitable for calculating and referenced in engineering design.
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