本論文對於多輸入多輸出技術之雙頻天線提出設計方法以應用於無線區域 網路802.11 n之2.4 GHz與5 GHz頻段。此天線架構為印製在印刷電路板FR4上，
所以有製作簡單、成本低、整體的面積小、易與其他電路結合、不需要額外的集 總元件做匹配等優點，天線所設定的環境並不大，為相鄰之兩空間13 × 5.5mm2 和18 × 6.5mm2，分別放入兩支雙頻天線1與天線2，但天線2空間兩面為地，另外 天線環境空間高度不高以及空間不對稱，更加深了此雙頻天線的設計困難度，因 此採用倒L形天線耦合四分之一波長諧振器，讓兩共振機制同時匹配於兩頻段以 達到雙頻天線效果，而兩個共振機制幾乎是可看成互相獨立，所以對於調整各自 共振頻率上有很大的方便，另外固定天線之間倒L形天線與寄生元件的耦合量，
可在影響頻寬不大的狀況下更易於觀察隔離度隨著參數的變化。
對於隔離度改善之天線設計，首先依據避免兩天線之強烈電容性耦合與電感 性耦合來確立天線之擺放形式，以避免天生架構對隔離度不良的窘境，依據此原 則對於所需頻寬來初步設計，接下來為了簡化隔離度不良的問題，將天線1架構 固定不動，討論天線1對天線2之耦合情況，觀察高低頻之隔離度，將耦合情況分 類分析，針對問題對症下藥，可有效的改善隔離度。對此天線實際量測結果，低 頻隔離度為8.09dB高頻隔離度為12.65dB，隔離度改善之方法希望能提供現行無 線通訊產業在天線設計上正面的幫助。
本論文為針對應用於 USB 無線網路卡之雙頻 MIMO 天線作討論，對於不 對稱之空間中提供雙頻的隔離度改善方法有深入的探討，天線的環境設定如 3.1 中所示，而此 USB 無線網路卡實際應用於筆記型電腦或個人電腦之使用環 境對於天線特性之影響，在實做量測所得結果中平均輻射增益降低 2dB 上下，
是由於 USB 無線網路卡上之電流流向主機板而影響輻射，解決方式可在主機 板與 USB 接頭之間加上高頻阻絕(RF chock)以避免電流流向主機板。
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