步階阻抗之地缺陷結構用於具備高頻抑制之寬頻微帶線帶通濾波器

隨著新一代的無線通訊系統快速發展，利用高頻率與天線陣列等技術，可大幅提高資料傳輸量。但是仍有許多困難尚待解決，例如於有限的使用頻譜，須盡量降低發射與接收頻段之間的干擾，且同時微型化各類行動通訊裝置，在有限的體積下，內部元件必須精度高與特性佳。被動式濾波器是通訊系統中一個重要的元件，能減少接收的雜訊與降低發射/接收間的干擾，因此本研究將著重於濾波器設計。本文提出微型化微帶線帶通濾波器，具備寬頻、高階數、高頻諧波抑制的特性。設計上使用一些方法來達成上述特性：步階阻抗共振腔、串聯電容耦合共振腔、插槽效應和缺陷性接地結構。其中地缺陷結構的目的在於增加電流路徑，藉此產生更強的慢波效應，增加結構的電感性，可縮小原本濾波器所需要的面積，除此之外，藉由控制電流路徑為特定長度使其可形成一個共振腔，它還可以增加濾波器整體的階數。本研究首先根據濾波器理論搭配三維全波電磁模擬設計微帶線濾波器，接著利用標準電路板製程製作並用向量網路分析儀量測其特性，根據量測結果，本文所提出的濾波器具備68%的通帶頻寬與無高頻諧波，且體積小於一般微帶線濾波器。

關鍵字

缺陷性接地結構；步階阻抗共振腔；寄生頻率抑制；微帶線；寬頻帶通濾波器；插槽效應

並列摘要

With a fast development of wireless communication systems, data-transfer rates are increased sharply via some technologies including high frequency and antenna arrays. However, there are several challenges such as limited bandwidth where the interferences between the transmitting and receiving bands need to be reduced and miniaturized for portable devices where the components inside the devices need to have high accuracy and good qualities. Passive filters are key components of communications systems for eliminating the received noised levels and interferences between the transmitted and received bands. In this research, we proposed a miniaturized microstrip bandpass filter with several characteristics including wide-band, high-order, harmonic-frequency suppression. To achieve above features, some design methods were introduced including stepped-impedance resonators, series-coupling resonator, H-slot, and defected ground structures (DGS). The advantage of DGS was to increase the current path for strong slow-wave effect by increasing the overall inductance of the structure. In addition, it could increase the orders of the filters for sharp roll-off responses. In this research, a prototype was designed based on the filter theory and 3D full-wave EM simulations. It was fabricated via PCB standard photolithography and measured with a calibrated vector network analyzer (VNA). Based on the measurement results, the proposed filter had a 40% fractional bandwidth, harmonic-suppressed merit, compact size.

並列關鍵字

Defected Ground Structure ； Stepped Impedance Resonator ； Spurious Frequency Suppression ； Microstrip Line ； Wideband Bandpass Filter ； Slot Effect

參考文獻

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步階阻抗之地缺陷結構用於具備高頻抑制之寬頻微帶線帶通濾波器

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