本文選題：電磁泄漏　切入點：電磁屏蔽　出處：《華北電力大學》2015年碩士論文　論文類型：學位論文

【摘要】：電磁屏蔽是通過場耦合途徑抑制電磁干擾的主要技術。它的實現(xiàn)可通過使用一個金屬外殼包圍干擾源,以降低其場泄漏,或減少外部磁場強度來篩選敏感對象。雖然一個封閉的金屬外殼對于電磁波具有非常高的屏蔽效能SE,但是因為一些實際功能,外殼上不可避免的會出現(xiàn)小孔,小孔的存在會導致SE顯著減少。通常,在用于SE測量的標準方法中,一個屏蔽外殼的SE被定義為沒有外殼時給定點的場強與外殼存在時該點的場強之比。其中,要求場源被放置在外殼外部。換句話說,場的觀察點是在外殼內(nèi)部,其優(yōu)點是減少了其他不必要的干擾源對所接收場強的潛在影響。所以,在許多文獻中對于SE的評價都是對于外部場源。然而,相反的情況下,源在外殼內(nèi)部也具有實際意義,值得予以關注。原則上,這兩種情況可根據(jù)互易原理相互轉化。然而,由于對“外部源”實例尚未進行全面和深入的研究,我們不能為每個“內(nèi)部源”實例找到合適的“對偶問題”。例如,對于后者,在近場區(qū)域中的場分布是主要考慮的問題,但是對于前者,激勵源(通常假設是平面波)在遠場區(qū)定位明顯。本文首先基于模式展開方法得到的解析公式,計算了電偶極子天線激勵下矩形屏蔽體的電磁場分布,獲得了屏蔽體內(nèi)壁和內(nèi)部的電場和磁場分布特性。接著,提出了一種用于計算開孔矩形腔體電磁泄漏場的解析理論模型。該理論模型先基于模式展開法求解封閉腔場,進而依據(jù)Bethe小孔耦合理論將泄漏場與封閉腔場用等效偶極子關聯(lián)。該模型可以考慮波頻率、場源位置、開孔位置及場強觀測點位置等因素的影響,計算結果與全波仿真結果一致。最后,提出了一種用于計算封堵孔矩形腔體電磁泄漏的解析理論模型。該模型同樣先基于模式展開法求解封閉腔場,進而用平面波垂直入射無限大導體的邊界條件近似計算出透射場的切向分量,最后通過面磁流在空間產(chǎn)生的電場求解出封堵孔的泄漏場分布。
[Abstract]:Electromagnetic shielding is the main technology to suppress electromagnetic interference through field coupling. It can be realized by using a metal shell to surround the interference source to reduce its field leakage. Or reduce the external magnetic field intensity to screen sensitive objects. Although a closed metal shell has a very high shielding efficiency for electromagnetic waves, because of some practical functions, there are inevitable small holes in the shell. The presence of small holes can result in a significant decrease in SE. Generally, in standard methods for SE measurement, SE of a shielded shell is defined as the ratio of the field strength given to a given point in the absence of a shell to the field strength of the point at which the shell exists. The field source is required to be placed outside the shell. In other words, the field's observation point is inside the shell, which has the advantage of reducing the potential impact of other unnecessary interference sources on the received field strength. In many literatures, the evaluation of SE is for external field sources. However, on the contrary, the source also has practical meaning inside the shell and deserves attention. In principle, the two cases can be converted to each other according to the reciprocity principle. Since there has not been a comprehensive and in-depth study of "external source" instances, we cannot find an appropriate "dual problem" for each "internal source" instance. For the latter, for example, the field distribution in the near-field region is the main consideration. But for the former, the excitation source (usually assumed to be a plane wave) is obviously located in the far field. Firstly, based on the analytical formula obtained by the mode expansion method, the electromagnetic field distribution of the rectangular shielding body excited by the electric dipole antenna is calculated. The distribution characteristics of electric field and magnetic field in the shielding wall and inside are obtained. Then, an analytical theoretical model for calculating electromagnetic leakage field of rectangular cavity with open hole is proposed. The theoretical model is based on the mode expansion method to solve the closed cavity field. Furthermore, the leakage field and the closed cavity field are correlated by equivalent dipole according to the Bethe small-hole coupling theory. The model can consider the influence of the wave frequency, the location of the field source, the location of the opening hole and the position of the observation point of the field strength, and so on. The calculated results are consistent with the full wave simulation results. Finally, an analytical theoretical model for calculating electromagnetic leakage of a rectangular cavity is proposed. The model is also based on the mode expansion method to solve the closed cavity field. Then the tangential component of the transmission field is approximately calculated by the boundary condition of the infinite conductor vertically incident by plane wave. Finally, the leakage field distribution of the sealing hole is solved by the electric field generated by the surface magnetic flow in the space.
【學位授予單位】：華北電力大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN03

【參考文獻】

中國期刊全文數(shù)據(jù)庫 前3條

1 周金山,劉國治,彭鵬,王建國;不同形狀孔縫微波耦合的實驗研究[J];強激光與粒子束;2004年01期

2 焦重慶;齊磊;;平面波照射下開孔矩形腔體的電磁耦合與屏蔽效能研究[J];物理學報;2012年13期

3 李小澤;滕雁;王建國;宋志敏;張黎軍;張余川;葉虎;;過模結構表面波振蕩器模式選擇[J];物理學報;2013年08期

，

本文編號：1621595