臺灣博碩士論文加值系統

本論文探討使用偶極天線模型估算由封閉金屬外殼上之連接線產生的共模輻射。首先，使用CST Microwave Studio對接線封閉金屬外殼做全波模擬，並觀測遠場的電場數據作為實驗數據，並使用其傳輸線上的電流數據做進一步的分析。接著，我們將接線封閉金屬外殼之模型使用映像法近似成偶極天線的模型，同時將模型中的接地面以相同方式考慮其效應。

利用CST Microwave Studio中傳輸線上多點電流積分求得的遠場結果與CST Microwave Studio模擬的遠場結果做比較，藉此佐證使用近似模型的合理性。然而，實際在測量時並無法以電流探棒將傳輸線上的所有電流數值求出，因此我們以CST MWS中傳輸線上特定兩點的電流數值充當實際測量中以電流探棒測量的數值，並以弦波代表傳輸線上電流的分布，並將其代入簡單的解析公式有效估計共振模態時的遠場電場值。如此一來我們可以減少產品在無反射實驗室測試的時間與測試需要花費的大量金錢。

This thesis proposes a method of predicting the far-field radiation from cables attached to a conducting enclosure at the early stage of the design and development phase without using an EMI chamber. The method combines an equivalent dipole model approximating with sinusoidal current distribution and Common-mode current measurement at some specified locations on the cable. First, we use CST Microwave Studio to simulate the whole setup mentioned above to obtain the far-field radiation as the measurement data and to extract the current distribution on the cable for further analysis. By using the image method, we approximate the conducting enclosure with a cable attached to by a dipole model, and introduce current images to take the ground into account.

The proposed model is examined by comparing the field data by CST and that from the far-field integral with the current distribution by CST. In practice, the current distribution along the cable cannot be obtained everywhere, but CM current can be measured at a couple of points by the current probe, and the measured current acts as the amplitude of an assumed sinusoidal distribution. This approach results in simple analytical formulas to evaluate far field components, which greatly reduces time and cost by a full-wave solver or by real measurement in the anechoic chamber.

摘要 I
Abstract II
目錄 III
圖目錄 IV
表目錄 V
第一章 序論 1
1.1 研究動機與目的 1
1.2 文獻回顧 1
1.3 章節概要 2
第二章 受測物體之模擬環境設置 3
2.1 EMI實驗室設置 3
2.2 模擬之模型 5
2.3 模擬之觀測 8
第三章 近似接線金屬盒之模型與修正公式 10
3.1 接線金屬盒之平均表面電流分佈與遠場結果 10
3.2 近似模型與表面電流密度求得結構之遠場輻射 14
第四章 接地金屬盒之近似模型與修正公式 17
4.1 接地金屬盒之近似模型 17
4.2 接地金屬盒之水平結構分析 19
4.3 接地金屬盒之垂直結構分析 26
4.4 接地金屬盒之完整結構分析 31
第五章 改變金屬盒尺寸之影響 39
第六章 結論 44
參考文獻 45

[1] J. Wang, K. Sasabe, and O. Fujiwara, “A simple method for predicting common-mode radiation from a cable attached to a conducting enclosure,” IEICE Trans. Commun., vol. E85-B, no. 7, pp. 1360-1367, Jul. 2002.
[2] H. Tarumoto et al., Proc. IEICE Gen. Conf., B-4-36, March 2000.
[3] Hyun Ho Park, Hark-Byeong Park, and Haeng Seon Lee, “A simple method of estimating the radiated emission from a cable attached to a mobile device,” IEEE Trans., vol. 55, no. 2, pp. 257-264, Apr. 2013.
[4] S. Deng, T. Hubing, and D. Beetner, “Estimating maximum radiated emissions from printed circuit boards with an attached cable,” IEEE Trans. Electromagn. Compat., vol. 50, no. 1, pp. 215-218, Feb 2008.
[5] H. W. Shim and T. H. Hubing, “Model for estimating radiated emissions from a printed circuit board with attached cables due to voltage-driven sources, “IEEE Trans. Electromagn. Compat., vol. 47, no. 4, pp. 899-907, Nov. 2005.
[6] S.A. Schelkunoff and H.T. Friis, “Antennas Theory and Practice,” John Wiley &; Sons, 1952.
[7] Microwave Studio. ver. 2011. (Dec. 2011). CST Corporation, Darmstadt, Germany [Online]. Available: http://www.cst.com
[8] Henry W. OTT, “Electromagnetic compatibility engineering,” John Wiley &; Sons, 2009.