传输线理论在光纤陀螺寻北仪电磁屏蔽中的应用研究

发布时间：2018-04-05 21:42

本文选题：传输线理论　切入点：平面电磁波　出处：《北京交通大学》2014年博士论文

【摘要】：摘要：为了抵抗电磁干扰对电子设备的影响,电磁屏蔽正不断发展起来,并广泛应用于各个领域。虽然现在有很多数值方法可以得到较为精确的电磁仿真数据,但其耗费时间长,CPU的计算量大。因此,应用解析法建立完善的电磁屏蔽模型正逐渐成为指导工程实践的快捷有效的方法。本文以光纤陀螺寻北仪为研究对象,应用解析法中的传输线理论,对实际工程中出现的典型屏蔽腔体分别进行了较为完整的建模。其中包括单层带孔缝腔体、双层带孔缝腔体、双面带孔缝腔体以及内置PCB板的腔体,并求解出了其中任意点的屏蔽效能,为工程实践中屏蔽腔体和孔缝的设计,及其内部器件的安排布局提供了很好的参考价值。论文的主要工作和创新如下： 1.针对平面电磁波以任意角度射入腔体的实际情况,提出在建模中引入平面电磁波的竖直入射角、水平入射角与极化角的方法。把平面电磁波的坐标从入射源坐标系转换到矩形腔坐标系,并按照电磁波的水平极化分量和垂直极化分量分别对模型进行分析研究。此建模方法使得平面电磁波可以以任意角度射入腔体,增强了模型对实际情况的拟合性。 2.针对孔缝处于腔体面的任意位置的实际情况,提出把孔缝建模成宽度不对称的共面带状线的方法。应用在平面电磁波辐射下的分布电源传输线模型对孔缝进行建模,并求出在孔缝中心处产生的等效电压,以此电压做为后续电路的电压源。此建模方法节省了计算时间,把孔缝从腔体面的中心位置扩展到了任意位置,扩大了模型对工程实践的适用性。 3.针对探测点处于矩形腔内任意位置的实际情况,提出结合模式电压和模式电流来表示矩形谐振腔内电磁场分布的方法。把矩形腔体看成一端完全开放,另一端完全封闭的矩形波导。此波导与孔缝相结合,应用集总电源传输线模型进行分析,考虑TE模和TM模的高次模影响,并结合腔体内的电场分布,求解出腔体内任意点的屏蔽效能。此建模方法把探测点从腔体内孔缝中心线上的点扩展到了腔体内的任意点,增强了模型的工程实践价值。 4.针对光纤陀螺寻北仪,依照以上建模方法,分别建模求取了单层、双层和三层带孔缝腔体的屏蔽效能。并研究了带孔缝腔体内屏蔽效能与探测点位置之间的关系以及腔体层数与屏蔽效能之间的关系。仿真结果表明：此模型得出的屏蔽效能值与实验测得的数据相吻合,证明了此模型的正确性。腔体的屏蔽效能随探测点的位置不同而不同,且均随腔体层数的增加而有所提高。为工程实践中对屏蔽效能要求比较高的设备或系统提供了很好的参考价值。 5.针对光纤陀螺寻北仪,研究了在平面电磁波照射下的双侧面带孔缝的矩形腔以及内置PCB板的带孔缝矩形腔体的建模,并求出了腔体内任意点的屏蔽效能。仿真结果表明：腔体的屏蔽效能随探测点的位置不同而不同,此建模方法具有一定的工程实践价值。
[Abstract]:Abstract: in order to resist the electromagnetic interference of electronic equipment, electromagnetic shielding is constantly developed and widely used in various fields. Although there are many numerical methods for electromagnetic simulation can get more exact data, but it takes a long time, CPU has large amount of calculation. Because of this, the analytic method is used to establish the model to improve the electromagnetic shielding it has gradually become a quick and effective way to guide the engineering practice.
The fog north finder as the research object, using the analytical method of transmission line theory, the typical shielding cavity in the actual project were established relatively complete. Including the single cavity with apertures, double cavity with apertures, with double cavity with aperture cavity and built-in PCB board. And calculate the shielding effectiveness of the shielding design for any point, the engineering practice of cavity and aperture, and the internal device layout provides a very good reference value. The main work and innovation are as follows:
1. according to the actual situation of plane electromagnetic wave with arbitrary incident angle of the cavity, introduced into the vertical incident plane electromagnetic waves in the modeling method of horizontal angle, incident angle and polarization angle. The coordinates of plane electromagnetic wave incident from the source coordinates to rectangular cavity coordinates, and in accordance with the analysis of electric magnetic wave horizontal polarization component and vertical polarization components are respectively the model. The modeling method of the plane electromagnetic waves at an arbitrary angle into the cavity, enhance the fit of the model to the actual situation.
2. according to the actual situation in the slot cavity at any position of the decent, put forward the modeling method of slot width of asymmetric coplanar stripline. The distribution of power transmission line model is applied in the plane electromagnetic wave radiation to simulate the aperture, and calculated the joint effect voltage generated at the center of the hole, this voltage as the voltage source follow circuit. This modeling method saves the computing time, the slot extends from the center to the position of cavity surface at any position, expand the applicability of the model in engineering practice.
3. according to the actual situation in any position detecting points in rectangular cavity, combining with the mode voltage and mode current to represent the electromagnetic field distribution of rectangular resonant cavity. The rectangular cavity as is completely open, the other end of the rectangular waveguide is completely enclosed. The waveguide and slot combination application of lumped power transmission line model were analyzed. Considering the influence of higher modes of TE mode and TM mode, and combined with the electric field distribution inside the cavity, calculate the shielding effectiveness of the cavity at any point. This modeling method the detection point from the cavity hole center line point is extended to an arbitrary point within the cavity, enhances the model of engineering practice.
4. for the fog north seeker, in accordance with the above modeling methods, modeling for single layer, double layer and three layer cavity with apertures on the shielding effectiveness. And to study the relationship between the joint relationship between cavity shielding effectiveness and detecting position and number of layers and the shielding cavity with holes. The simulation results show that: the shielding effectiveness value derived from the model are in good agreement with the experimental measured data, prove the correctness of this model. The shielding effectiveness of the cavity with the detecting point is different, and the increase of the number of the cavity is improved. It provides a good reference value for the engineering practice of shield efficiency requirements high equipment or system.
5. for the fog north seeker, on the side of the double plane electromagnetic wave irradiation with apertures of the rectangular cavity and a built-in PCB plate with apertures of the rectangular cavity model, and calculate the shielding effectiveness of the cavity at any point. The simulation results show that the shielding effectiveness of the cavity with different detecting point and different, this modeling method has a certain practical value.

【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN96

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