辐射体的近场-远场变换研究

发布时间：2019-07-06 19:51

【摘要】：随着现代科技的高速发展,电子设备越来越趋向于集成化与小型化,同一系统中包含各种功能与作用的电子器件,不可避免的会产生电磁干扰,而且现代所用的材料也趋向于轻型化,这种材料虽然使得使用及携带方便,但是跟传统金属材料相比,它的电磁屏蔽能力较差,容易造成电磁泄露。在一定的空间限制下,这些设备或系统工作时,尤其是那些精密仪器,对周围环境的要求非常高,可能环境中极小的电磁扰动就会对其性能造成影响。另一个侧面,这些电子设备一旦与其他设备一起工作时,它无意发出的电磁波也可能会造成系统的其他功能不能正常运行。这些有意或者无意的电磁干扰或者电磁泄露可能通过电波传播对远距离仍然会造成一定的电磁能量辐射,本课题解决的问题就是通过对电子设备或者系统辐射的近场电场进行推导求出其造成的远场电场限值,并对近场测试采样方法及采样误差分析进行分析。首先,根据平面波谱展开原理,研究了近场-远场外推原理,由近场辐射场得到了远场电场表达式。利用罗伦兹(Lorentz)互易原理推导近场-远场变换时耦合积及补偿方法,分析了不同的采样测试间隔对近场-远场变换算法得到的结果的影响,为后续数值模型分析提供理论基础。其次,以偶极子阵列作为辐射体仿真模型,将采样测试平面上的近场电场值带入近场-远场算法中得到仿真E面远场电场表达式,并与理论的相对比,得到在一定的误差范围内,仿真得到的方向图和理论方向图是吻合的。考虑实际条件,将地面对辐射体的影响分析,讨论了地面不同高度近场辐射值对远场辐射的影响情况。最后,对测量过程中的取样误差问题进行分析,其中讨论了三种误差源:随机幅相测量误差、有限面截断误差、探头定位误差,分析其对近场测量数据的影响,进而分析对远场电场值的影响。针对每一种误差源,均将其引入到仿真模型中,对其取不同大小误差值进行对比分析,得到了其误差上界,并通过误差补偿方法进行修正。
文内图片：

图片说明：直角坐标系下的平面测量方法
[Abstract]:With the rapid development of modern science and technology, electronic equipment tends to be integrated and miniaturized more and more. The electronic devices containing all kinds of functions and functions in the same system will inevitably produce electromagnetic interference, and the materials used in modern times also tend to be lightweight. Although this material makes it easy to use and carry, compared with the traditional metal materials, its electromagnetic shielding ability is poor and easy to cause electromagnetic leakage. Under certain space constraints, when these equipment or systems work, especially those precision instruments, the requirements for the surrounding environment are very high, and the performance of these equipment or systems may be affected by the very small electromagnetic disturbance in the environment. On the other hand, once these electronic devices work with other devices, their unintentional electromagnetic waves may also cause other functions of the system to fail to function properly. These intentional or unintentional electromagnetic interference or electromagnetic leakage may still cause certain electromagnetic energy radiation over a long distance through radio wave propagation. The problem solved in this paper is to calculate the far field electric field limit value caused by the near field electric field of electronic equipment or system radiation, and to analyze the sampling method and sampling error analysis of near field test. Firstly, according to the principle of plane spectral expansion, the principle of near-field-far-field extrapolation is studied, and the expression of far-field electric field is obtained from the near-field radiation field. The coupling product and compensation method of near-field-far-field transformation are derived by using Rolentz (Lorentz) reciprocity principle. The influence of different sampling test intervals on the results obtained by near-field-far-field transformation algorithm is analyzed, which provides a theoretical basis for the subsequent numerical model analysis. Secondly, using the dipole array as the radiator simulation model, the near-field electric field value on the sampling test plane is brought into the near-field-far-field algorithm to obtain the expression of the simulated E-plane far-field electric field, and compared with the theory, it is found that the simulated pattern is consistent with the theoretical pattern in a certain error range. Considering the actual conditions, the influence of the ground on the radiation body is analyzed, and the influence of the near field radiation value at different heights on the far field radiation is discussed. Finally, the sampling error in the measurement process is analyzed, in which three kinds of error sources are discussed: random amplitude and phase measurement error, finite plane truncation error and probe positioning error. The influence of the error on the near field measurement data is analyzed, and then the influence on the far field electric field value is analyzed. For each error source, it is introduced into the simulation model, and the error values of different sizes are compared and analyzed, and the upper bound of the error is obtained, and the error compensation method is used to correct it.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN601

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