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利用时域有限差分法对微波脉冲与带矩形孔缝的矩形和圆柱形腔体两种系统的线性耦合过程进行了研究。首先用数值方法分析了耦合过程中的场增强现象、脉宽展开现象和腔体调制现象,并发现了耦合过程中微波脉冲存在频谱分离现象。当微波脉冲的电场与孔缝窄边平行时,借助耦合函数对两个系统内部耦合场的分布特性进行了研究,结果表明在与孔缝窄边垂直的平面内,越靠近腔体壁,耦合场越弱。此外,两种腔体内部的耦合场在腔体截面内均呈现准周期振荡分布,矩形腔体内部耦合场振荡的幅值较均匀,而圆柱形腔体内部耦合场幅值在其截面中心附近区域最大;除了孔缝附近区域外,圆柱腔体轴线两端的耦合场远大于矩形腔体相应的耦合场。最后,研究了孔缝耦合共振频率与孔缝尺寸的关系,结果表明系统耦合共振频率不只与孔缝尺寸有关,而是由孔缝尺寸和腔体形状及其对微波脉冲的反射特性共同决定。
The time-domain finite difference method was used to study the linear coupling process of microwave pulses and rectangular and cylindrical cavities with rectangular apertures. Firstly, the phenomenon of field enhancement, pulse width expansion and cavity modulation in the coupling process are analyzed numerically and the spectral separation of microwave pulses in the coupling process is found out. When the electric field of microwave pulse is parallel to the narrow side of the aperture, the coupling properties of the two systems are studied by using the coupling function. The results show that in the plane perpendicular to the narrow side of the aperture, The weaker the field. In addition, the coupling fields inside the two cavities exhibit quasi-periodic oscillation distribution in the cross-section of the cavity, the amplitude of the coupling field oscillation in the rectangular cavity is more uniform, and the amplitude of the coupling field in the cylindrical cavity is near the center of the cross-section With the largest area. The coupling field at the two ends of the cylinder cavity is much larger than the corresponding coupling field of the rectangular cavity, except for the area around the aperture. Finally, the relationship between the pore-cavity coupling resonance frequency and the pore size was studied. The results show that the coupled resonance frequency of the system is not only related to the pore size, but also depends on the size of the pore, the shape of the cavity and the reflection characteristics of the microwave pulse.