材料的電磁特性量測技術已經研究了數十年，並廣泛應用於各種實際領域，如熱療法和食品品質控制。在科學方面，這些技術還促進了對分子動力學的研究，如弛豫時間和分子網絡結構。
在本研究中，我們提出了一個易於組裝的同軸波導系統，能夠提供材料在100 MHz到約17 GHz範圍內的寬頻介電係數和介磁係數曲線資訊。通過加入常見樣品，如空氣、庚烷和水，我們能夠利用Nicolson-Ross-Weir法校準系統並獲得頻率響應曲線。本方法可同時量測液體多個特性參數且非破壞性量測，我們在研究中呈現了甲醇、乙醇和兩種商業用磁流體的測量數據。
我們對甲醇和乙醇的介電常數結果與文獻研究結果高度一致。然而，在磁流體研究中，一些模型產生了不良的擬合結果。通過比較模型之間的差異我們得出結論，奈爾弛豫的磁導率貢獻應該被視為一個獨立的Debye型群，這意味著簡化的有效介質理論在多弛豫機制作用的情況下不適用。此外，鐵磁共振頻率的準確性顯著依賴於異向能和熱能的比值。這項工作提供的擬合參數不僅為闡述液體弛豫過程提供更明確的資訊，也在生物技術中具有應用價值，例如在熱療法中用於計算特定吸收速率，或在核磁共振成像中用作對磁流體對比劑的品質控制。

In this work, we propose an easy-to-assemble coaxial system, which is able to provide broadband permittivity and permeability information of material from 100 MHz to around 17 GHz. By inserting standard sample such as air, heptane, water, we are able to calibrate the system and get frequency response curve by the help of Nicolson-Ross-Weir method. The measurement offers as a non-destructive method to measure multiple interested parameters at a same time.
Our permittivity results of methanol and ethanol show good agreement with previous research from Barthel, J., et al. In ferrofluid research, however, some models make poor fitting results. By comparing the difference between models, we conclude the permeability contribution of Neel relaxation should be consider as a Debye-type group independently, which means simplified effective medium theory is not suitable in our case. Furthermore, the accuracy of ferromagnetic resonance frequency is significantly relied on the ratio of anisotropy energy and thermal energy. This work not only provide insight for liquid relaxation processes, also have application value in bio technology, such as decide the specific absorption rate in hyperthermia therapy, or as a quality control for ferrofluid using in magnetic resonance imaging as contrast agent.

致謝 i
Abstract iii
摘要 iv
緒論 1
1.1研究動機 1
1.2 介電係數 2
1.3 介磁係數 3
1.4 電磁特性量測方法 4
1.4.1 量測系統比較 5
1.4.2 不同傳導線系統比較 6
腔體設計 8
2.1 多段式腔體模型建立 8
2.2 TEM, TE, TM 本徵模式 9
2.3同軸波導管的高次模與腔體尺寸關係 11
2.4 Inventor模型與成品 15
實驗架設與數據取得 17
3.1 儀器與腔體架設 17
3.2 校正方法 17
3.3 取得實驗數據 19
3.3.1 Nicolson-Ross-Weir method 19
3.3.2 等效S參數與實驗數據取得 20
液體的電磁特性 22
4.1 等效介電 22
4.1.1 線性響應與介電弛豫模型 22
4.1.2 低元醇結果分析 24
4.2 等效介磁 26
4.2.1磁流體與單磁域粒子 26
4.2.2 布朗弛豫 (Brownian relaxation) 27
4.2.3 拉莫爾進動 (Larmor precession) 29
4.2.4 奈爾弛豫 (Néel relaxation) 35
4.2.5 等效弛豫時間與等效磁化率模型 38
4.2.6 磁流體數據分析 42
結論 46
References 48

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