左手共面波導及其應用

Left-handed Coplanar Waveguides and Their Applications

吳民首(Min-Sou Wu)

指導教授 ： 毛紹綱

國立臺北科技大學/機電學院/電腦與通訊研究所/碩士(2005年)

https://doi.org/10.6841/NTUT.2005.00314

摘要

本論文提出一個嶄新的左手共面波導結構，並且透過等效物質理論成功地萃取出有效介電常數與有效導磁係數，藉由萃取出的參數探討左手共面波導結構的基本特性，例如：在左手區間內有效介電常數與有效導磁係數同時皆為負值、群速度與相速度方向相反、傳播常數與折射率為負值、特徵阻抗值變化劇烈等特性，並且經由實驗與模擬的相互印證，得到左手共面波導結構不但可以在通帶範圍內取代傳統的共面波導結構，並且利用其相位超前的特性，可將電路作縮小化，而這些特性都是在研究左手材料時重要的參數與現象。
另外，由等效物質理論的觀念出發，本論文進一步提出左手共面波導結構的等效電路模型，經由理論推導出的串並聯電阻、電感、電容，同時包含了右�左手區間以及電路損耗的考量，藉由等效電路模型的建立，我們可以準確地預測其S參數的大小與相位的變化，幫助我們做更進一步的分析與探討。
在應用上，由於左手共面波導結構具有相位提前的特性，本論文所提出的複合式右�左手短路分支結構比起傳統的短路分支結構來的更短，並且將之應用在寬頻分支帶通濾波器上，不但縮小了傳統分支帶通濾波器的面積，在通帶過後的高頻部份也有較好的抑制效果。在窄頻帶通濾波器方面，利用左手共面波導取代傳統半波長傳輸線，整個濾波器的總長度比起傳統濾波器縮小約一半左右。最後，將此左手共面波導應用在雙頻帶濾波器上，能夠創造出二個相距甚近之通帶，且其設計方法也將在本論文中作詳細的探討。

關鍵字

左手共面波導 ； 等效物質理論 ； 等效電路模型 ； 相位提前 ； 分支濾波器

並列摘要

Novel composite right/left-handed (CRLH) coplanar waveguide (CPW) structures and their filter applications are investigated in this thesis. To understand the fundamental properties of the CRLH CPW, such as simultaneously negative permittivity and permeability, anti-parallel phase and group velocities, and the negative propagation constant and refractive index, the effective electromagnetic parameters are extracted based on the effective medium theory to investigate these unusual phenomena. Moreover, the equivalent circuit model including the RH, LH, and lossy characteristics is established so that the S-parameters of the proposed CRLH CPW can be predicted precisely.
Several applications based on the CRLH CPWs with phase-advanced characteristic are also developed, such as the wideband CRLH bandpass filter (BPF), narrowband CRLH BPF, and CRLH dual-band BPF composed of the CRLH CPW short-circuited stub. For the narrowband CRLH BPF replacing the conventional half-wavelength transmission line resonator to the CRLH CPW can obtain a significant size reduction. The wideband CRLH BPF, not only possesses a good rejection at higher frequency band but also the size is more compact than the conventional CPW BPF. Finally, a CRLH dual-band filter with close passbands and its design methodology are also proposed.

並列關鍵字

composite right/left-handed ； effective medium theory ； effective circuit model ； phase advance ； short-circuited stub

參考文獻

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