由於現今商業上有越來越多高頻段微波的應用，如汽車防撞雷達（Collision Avoidance Radar）、衛星通訊網路、短距點對點通訊等，而這些應用中有個共同的需求－高指向性（High-Directivity）天線。而為了因應現今無線通訊都朝小型、輕量、薄型、低功率與高性能的趨勢來發展，因此要設計出兼具以上特點的高指向性天線是有其困難度與必需性的。本文第一項重點是設計以微帶天線饋入的單頻率選擇平面共振式天線（共振腔1/2波長高），為了解決天線覆板面積縮小時，會有旁波瓣位準（sidelobe level）過大的問題，在共振腔的四周圍平面上，分別加上一對完美電牆與一對完美磁牆，並以四分之波長轉換器結合完美導體來實現完美磁牆，由模擬結果成功使得面積約為2 × 2 λ02 (其中λ0為波長) 的平面共振式天線之旁波瓣位準低於-25 dB，指向性大於13 dB，並且進行實做和量測。量測結果指向性為12.22 dB，E plane和H plane的旁波瓣位準分別-24.62 dB與－20.72 dB。本研究第二項重點是雙頻率選擇平面共振式天線（共振腔λ0/4高），相同的在共振腔的四周圍平面上，分別加上一對完美電牆與一對完美磁牆，但改以人工磁導體 (artificial magnetic conductor，AMC) 結合完美電牆來實現完美磁牆。模擬計算成功使得面積約為2 × 2 λ02 (其中λ0為波長)的平面共振式天線之旁波瓣位準低於-25 dB，指向性大於13 dB，如此一來可使整體的體積變得更小，也更有利於和其它產品整合。

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