微波波段材料特性量測

Material Characterization at Microwave Frequency

黃世睿

指導教授 ： 張存續

國立清華大學/理學院/物理學系/碩士(2013年)

https://doi.org/10.6843/NTHU.2013.00543

摘要

本篇論文旨在研究在微波波段材料特性量測方法，理論上建立精確演算機制，使量測到微波訊號可用以推知材料特性，實驗上設置一系列實驗流程，以達成精確量測，隨著材料特性與形狀之不同，需要相應量測方式，故本文可以分成兩個部分。
針對塊狀材料，本文使用穿透反射法來量測材料之複數介電常數與磁導率。在理論方面，透過新的演算法二階段擬合法，有效抑制由共振穿透所引起之計算不穩定性，並同時修正波導管造成之歐姆損耗。在實驗上，透過網路分析儀校正與使用，與波導管分析儀換位對接方式，平均消去實驗誤差，以達到精確量測。本文在Ka頻段(26.5-40GHz)量測Teflon與Al2O3之介電常數與磁導率，與傳統方式相較標準差小約十倍，故本文提出一高精確度、解析度寬頻量測方式。
針對厚膜，本文使用共振腔/共振腔微擾混和式方法量測材料之複數介電常數。在理論方面，透過時域分析概念，達成複數介電常數同時量測可能性。在實驗方面，透過高品質因子之共振腔之設計，放大厚模之效應，系統靈敏度大幅提升，有效測得厚膜之介電常數。本文測量11μm厚光阻SU-8 2050之複數介電常數，其介電常數實數部分為3.33，而虛部部分為0.08。

關鍵字

介電常數 ； 磁導率 ； 微波量測 ； 穿透反射法 ； 共振腔法 ； 共振腔微擾 ； 薄膜量測 ； 向量網路分析儀

並列摘要

This research focus on the mythology of material characterization at microwave frequency. According to shape and properties of material, different approach is required. There are two parts in this research.
The first part of this research concentrates on the mythology of complex permittivity and permeability measurement of a bulk material based on transmission/reflection method. A new algorithm known as Two Steps Parameter Fitting algorithm and well-defined experimental process were developed. Through the new algorithm, the algebraic instability caused by resonant transmission is successfully suppressed. And the effect of conducting loss was also taken into consideration. By the means of well-defined experimental process, the error of misalignment and other unwanted effect were averaged out. The complex permittivity and permeability of Teflon and Al2O3 were measured in Ka band. The fluctuation and standard deviation of complex permittivity and permeability derived by new method is at least ten times smaller than that derived by conventional method.
The first part of this research focuses on mythology of complex permittivity measurement for thick film. Theoretically, a cavity / cavity perturbation mixing method was proposed. And the important concept of time domain analysis of close cavity was clarified. Based on this concept, the capability of measuring the dielectric loss tangent of film was realized. Experimentally, a high sensitivity cavity measuring system was designed and fabricated. The effect of film is emphasized by the high Q cavity. And a set of well-defined experimental procedures is proposed as well as followed. Eventually, the complex permittivity of 11μm thick SU-8 2050 coated on quartz substrate was measured. Its real part of relative permittivity is 3.33 which is consistent with the provided datasheet. And its imaginary part of relative permittivity is 0.08.

參考文獻

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