本論文目標為設計與探討一個雙頻段、單一指向且高方向性之天線。天線主要架構是採用具有單一指向且高方向性的對數週期天線 (Log-Periodic Dipole Antenna，LPDA) 與八木天線 (Yagi-Uda) 做為選擇。偶極天線單元採用PS (Parallel Strip)進行各天線單元之串聯，將PS之特徵阻抗設定為50 Ω進行饋入。本文對數週期天線設計上不採用交叉饋入的方式進行天線之設計，由於傳統印刷式對數週期天線由短邊偶極天線單元處饋入，而利用改良天線架構之方式可以做到將訊號由長邊偶極天線單元處饋入之方法，再以八木天線串聯進行模擬與設計。
　　本論文天線設計於FR4之板材，在頻段規格上操作於2.4 – 2.484 GHz與3.3 – 5 GHz之雙頻段設計，而低頻段由八木天線建構，頻寬量測結果為2.39 – 2.66 GHz (11%)頻段，高頻段由改良式對數週期天線建構，頻寬量測結果為2.94 – 5.07 GHz (51.3%)頻段，在頻率2.45 GHz、3.5 GHz、4 GHz與4.5 GHz頻率點上之輻射場型前後比皆達15 dBi以上，使用全波模擬軟體為HFSS，電路模擬軟體為ADS。

Design of dual band uni-direction and high directivity antenna is presented in the thesis. The proposed antenna is consist of the uni-direction high directivity log-periodic dipole array (LPDA) and Yagi antenna. Both are constructed with series dipole elements by PS (parallel strip), and then the 50 Ω parallel strip as the antenna feed. The proposed LPDA antenna element dose not be adopt by cross feed. The traditional printed log periodic dipole antenna array is fed on the shortest dipole position. The proposed LPDA antenna, on the other hand, can be fed on the longest dipole positon by modified antenna arrangement. Then it is connected with Yagi antenna.
The presented antenna is designed with the dielectric substrate of FR4. The formulated frequency band is operated from 2.4 GHz to 2.484 GHz and 3.3 GHz to 5 GHz for dual band applications. The proposed antenna is constructed with the Yagi and the modified log-periodic dipole antenna. The bandwidth is measured from 2.39 GHz to 2.66 GHz in the low band and 2.94 GHz to 5.07 GHz in the high band. The front to back ratio upon to 15 dB at 2.45 GHz、3.5 GHz、4 GHz, and 4.5 GHz. The full-wave simulation software and circuit simulation software are HFSS and ADS, respectively.

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