本論文針對第五代行動通訊的通訊技術發展，全金屬背蓋手持式行動裝置天線做多天線系統之設計。由於內部天線擺放位置會受到金屬背蓋屏蔽效應，影響天線輻射特性，使得天線會有頻寬不足的問題。操作頻率於Sub-6 GHz的5G通訊之3.5 GHz頻帶，若僅使用倒F天線(Inverted-F Antenna；IFA) 頻寬約為140 MHz；而僅在金屬背蓋上切割肉眼看不見之寬0.1 mm極細槽孔天線(slit antenna) 頻寬約為100 MHz。為了增加頻寬，我們利用上層的倒F天線耦合激發金屬背蓋之槽孔天線，藉此將金屬背蓋作為天線之主輻射體，可增加天線輻射特性，提升天線工作頻寬。兩天線間有電耦合和磁耦合的產生，因此還可些微縮小兩天線的尺寸，藉由耦合效應設計倒F天線與槽孔相對間距及位置，頻寬可達到近300 MHz，以滿足5G藍圖之eMBB應用頻寬以達到規範頻寬。
　　建構手持式多天線系統時，將天線擺在四個角落，並藉由擺放的相對位置的不同，而有不同的隔離度之分析，在相同的擺放位置下，不需加其他隔離器而有較佳之隔離效果，與基地台天線建構傳輸平台，結合本文提出之多天線系統以建構4x4多輸入多輸出系統。在此架構下，可提供行動通訊之軟硬體發展以強化第五代行動通訊之應用技術。

The propose of this paper is aimed at the development of communication technology of the fifth generation (5G) mobile communication. We propose MIMO antenna system broadband antenna design for handheld devices with metal housing. Since the antenna is shielded by the metal housing, the antenna radiation characteristics are affected, causing insufficient bandwidth. The operating frequency we set is 3.5 GHz of 5G communication in Sub-6 GHz as a candidate spectrum for 5G network architecture in the world. In a handheld device with metal housing, if only the inverted-F antenna (IFA) is used, the bandwidth is about 140 MHz; and only the thin slot antenna with invisible width 0.1mm is used, the bandwidth is about 100 MHz. In order to broaden the bandwidth, we use the inverted F antenna at the upper layer to couple the slot antenna at the ground layer with the metal housing, increasing the radiation characteristics of the antenna and improving the operating bandwidth of the antenna. The relative position of the inverted F antenna and the slot antenna is the key of the coupling effect, causing the bandwidth reaches nearly 300 MHz to meet the 5G blueprint. The overall size of the two antennas can be slightly reduced by this kinds of mechanism as well.
The antenna elements are placed at four corners in a handheld device to construct a MIMO antenna system. Since the space of handheld device is finite, isolation analysis is presented. We combine the proposed structure with the base station antenna to construct a MIMO communication platform, constructing a 4x4 MIMO system. Under this framework, the development of software and hardware for mobile communication can be provided to strengthen the application technology of the fifth generation mobile communication.

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