本論文主要開發應用在無線通訊產品上的薄型化智慧型陣列天線，以提升傳輸效能 與系統抗干擾能力。於硬體實現上以陣列天線搭配切換式波束成型模組，透過偏壓控制 提供每個天線單元不同的相位差，可令主波瓣指向不同方向。為配合無線區域網路應 用，本研究擇定陣列天線設計中心頻率為2.4 GHz，並採用矩型貼片天線作為天線單元， 以利實現薄型化設計。首先，以設計天線間距分別為0.38 、0.44 、0.5 的4×1 線性天線陣列版本，評估天線間距對於主波辦指向角度的影響。為了達到波束掃描的效 果，於陣列天線背板掛載切換式波束成型模組。該模組以薄膜積體被動元件製程實現， 搭配以橋式T 線圈實現的微型化SP4T 切換開關及4×4 巴特勒矩陣，從而達成微型化與 薄型化設計。實測之反射損耗於通帶2.35 GHz 到2.45 GHz 皆大於15 dB，實測之輻射 場型亦如預期，達到切換四個方向的一維掃描指向效果。經評估天線間距為0.5 時有 較佳波束掃描效果，作為二維4×4 陣列天線設計之天線間距。藉由組合五個前述波束成 型模組，本研究實現可切換十六個指向的二維波束掃描陣列天線。各方向實測之反射損 耗於通帶2.35 GHz 到2.45 GHz 中皆大於20 dB，量測所得之波束指向亦與模擬相符合。 整體電路尺寸大小為320 mm ×312 mm ×3.25 mm，達到輕薄化且微小化的設計目標。;The goal of this study is to develop a low-profile smart antenna array for wireless communication applications to improve the transmission efficiency and the suppression of interferences. The proposed smart antenna array is implemented with compact switched beamformer modules and a patch antenna array. It can direct the main beam to different directions by providing the input of each antenna element with different phase. Microstrip patch antennas of center frequency f0 = 2.4 GHz is used for the antenna elements to achieve a low-profile design. First, three 4×1 linear antenna array designs with antenna spacings equal to 0.38 ,0.44 and 0.5 are implemented to evaluate the effect of antenna spacing on the radiation pattern IPD-based beamformer module. The module is mounted on the backside of antenna PCB to achieve beam steering. In order to achieve compact circuit size and low-profile, bridged-T coils are employed to realize the absorptive SP4T switch and the 4×4 Butler matrix of the IPD-based beamformer module.The measured input return loss of the 4×1 antenna array is better than 15 dB from 2.35 to 2.45 GHz, and the main beam can be successfully steered to 4 different directions. Also, it is found that the antenna spacing of 0.5 can achieve best side lobe suppression so it is used for the following proposed 4×4 planar patch array. Five proposed beamformer modules are employed to form the 2-D beamformer for the 4×4 patch antenna array with 16-beam directions. The measured input return loss of the 4×4 antenna array is better than 20 dB from 2.35 GHz to 2.45 GHz, it can successfully steer the main beam to sixteen pre-defined directions two-dimensionally. The size of the 2-D scanning antenna array is 320 mm × 312 mm with a low-profile of only 3.25 mm, which meets the design target of compact size and low-profile smart antenna system.
