無線通訊網路系統的日益發展帶動著行動產品發展與創新。現今對於行動通訊產品的基本需求為輕、薄、短、小、低成本、多功能與多頻帶的操作之外，具備高速的無線傳輸速度也是不可或缺的條件，但是將上述條件與高規格的規範實現於產品時，將會提高整體設計的困難度。在無線通訊系統中，前端的天線是重要的傳輸/接收訊號端，對於現今通訊協定採用更加嚴格的標準，在設計天線的條件包含高性能、小尺寸、重量輕、低成本和多頻段，因此設計微型化多頻帶操作的天線是相當有挑戰性的課題；此外伴隨著電子產品的微小化，在有限的面積下配置多種功能的元件，此舉將提高內部訊號和外部訊號的相互電磁干擾(EMI)，也興起我們探討元件設計與雜訊抑制的動力。高速無線傳輸速度的大演進，更加嚴格要求前端天線的規格，使得舊有的單輸入單輸出系統逐漸淘汰，取而代之的多輸入多輸出系統開始興起，同時衍伸出內部訊號之間的干擾問題，讓傳輸速度提升率受限，所以改善多天線通訊之間的干擾是相當重要的議題。
本論文首先將提出一種天線的設計架構，並且透過簡易的印刷電路板技術達成實作，其特性具有長期演進系統(LTE)和無線廣域網路(WWAN)系統的單極天線，因此天線可應用於攜帶式的無線通訊設備上，其設計概念採用雙分支的單極饋入輻射體與接地面的耦合金屬體和匹配金屬條作為共振機制，並且可以激發640-875 MHz 和1255-2815 MHz的雙頻帶，藉由上述設計機制皆可符合第四代通訊協定和無線廣域網路的頻帶。上述天線可由模擬與量測的反射損耗、輻射場型、增益和效率等證明多頻帶的單極天線擁有良好特性。
論文的第二部分探討產品內部的高頻電磁干擾問題，在文中我們提出具有吸收能量功用的導電薄膜，將導電薄膜放置於電路中可視為低通濾波器，同時提供良好的帶通響應。本文選用的導電薄膜材料為碳黑，其碳黑薄膜有幾項令人期待的性質，如高電阻率、可於低溫製程製作和低成本，更吸引人的是可藉由調整碳黑的比例控制吸收能量的起始頻率點，並由實驗量測可觀察出碳黑薄膜能有效的吸收高頻的能量。
論文的第三部分探討多輸入多輸出系統的隔離度改善，藉由上述碳黑薄膜的吸收能量功能，我們提出一種新的方法，在多輸入多輸出系統中加入碳黑薄膜，透過碳黑薄膜吸收干擾訊號，並且由量測數據證明S參數、輻射場型、增益、輻射效率和相關包絡係數等特性符合商業的標準。

Currently, wireless communication networks are developing rapidly, and the trends for mobile products include being creative and innovative. There is a need for mobile communication products to be compact in size, light weight, low-cost, multi-function, and characterized by multi-band operation. Additionally, it is also important to have a high wireless communication data rate. However, the above conditions and stricter specifications make designing products more difficult. In a wireless communication system, antennas are important transmitters/receivers. Emerging applications such as wireless communication protocols continue to challenge RF/microwave antennas with ever more stringent requirements, including being high performance, compact, light, low-cost, and multi-band. Thus, determining how to design a multi-band, miniaturized antenna is a big challenge. Furthermore, the inside of compact electronic products has many function devices that increase the electromagnetic interference (EMI) between interior and exterior signals, resulting in a need to research the power absorption in electronic devices and transmission lines.
Due to the evolution of high speed wireless transmission, the standards of front antennas have become stricter, so single input single output (SISO) systems are gradually being replaced by multiple input multiple output (MIMO) systems, resulting in interference between the antennas and limiting the transmission speed at the same time. Thus, improvement in the degree of interference between two or more antennas is a popular topic now.
First, an LTE antenna design structure is proposed and easily fabricated using a printed circuit board (PCB) process. The properties of the proposed monopole antenna are a Long Term Evolution (LTE) and wireless wide area network (WWAN) that can be applied in mobile equipment. The designed method is a combination of one monopole that is direct-fed within two branches and a couple-fed monopole with an impedance matching metal strip that connects to the ground and operation bands based on 6-dB return lossesof640-875 MHz and 1255-2815 MHz in the lower and higher bands, respectively. This method conforms with the fourth generation (4G) and WWAN operation bands. Simulations and measurements of monopole antenna return loss, radiation pattern, gain and efficiency, etc. are used to prove that the characteristics of this method are good.
In the second section, we discuss the problems with the EMI of products. In this dissertation, a conductivity film is proposed to be a power absorber, which when added in the circuits, is like a low-pass filter. The conductivity film material is carbon black whose properties are expected to exhibit high resistance, and a low temperature, low cost process, especially due to the proportion of carbon black used to control the starting absorption frequency. The measured results indicate that the carbon black film absorbs the high frequency power effectively.
In the third section, the improvement in the isolation of the MIMO system is discussed. We propose a novel method taking advantage of the absorbability of the carbon black film by adding a carbon black film in the MIMO system. Carbon black film absorbs interference noise and proves that the measured S-parameter, radiation pattern, peak gain, efficiency, and envelope correlation coefficients, etc. meet the commercial standards.

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