雙摺疊迴圈所構成之正交極化方向近場磁場探針

Abstract

本論文提出一使用兩個折疊式的導線迴圈同時量測雙極化方向磁場的近場量測探針。和傳統的磁場探針相比，使用雙迴圈可以同時量測兩個正交極化方向，縮短測量所需要的時間。折疊式的迴圈設計可以在維持相同的靈敏度時，縮小探針的體積。兩方向的訊號接收採用差模和共模訊號區別，簡化後端訊號處理的難度，亦去除了部分的電場耦合。設計上使用可藉由印刷電路板等製程達成的結構，因此可有效縮小化並更容易製作，減少不連續造成之寄生效應和共振現象。本探針之共振頻率為5.8 GHz，在0.1 GHz至4.5 GHz的使用頻寬間可有效同時測量兩方向之磁場，並且有著6 dB以上之對抗電場耦合雜訊的幅度，差模訊號更可以將電場耦合進一步降低至低於磁場耦合15 dB以上。

Near-field magnetic probes are often used to measure the magnetic fields above a printed circuit board in order to identify the sources and coupling paths of an electromagnetic interference (EMI) or radio frequency interference (RFI) problem. This thesis introduced a magnetic probe structure using two folding loop to measurement magnetic fields in two orthogonal direction. This orthogonal-direction magnetic probe using differential-mode signal and common-mode signal to distinguish orthogonal magnetic fields, has better sensitivity and E-field coupling suppression than traditional orthogonal magnetic probe. The effects of this probe are analyzed using full-wave simulations and measurements.