| 摘要: | 本論文研製可繞式小型平面(planar)偶極天線，天線設計於軟性印刷電路板 (Flexible Printed Circuit Board，FPCB)上，此類基板具質量輕、板厚薄，及高可繞之特性，天線結構上採用zigzag 之曲折設計達到小型化之目的。所設計之天線可置於硬式聚氨酯之模具中，實現平面、拋物面彎曲、圓柱彎曲、橢圓柱彎曲等型式之可繞天線，論文中針對可繞天線之輻射特性進行模擬分析與比較，藉以瞭解zigzag 天線基板彎曲時所產生之特性變異。模擬結果經由天線實作量測驗證，模擬與量測結果發現，天線基板彎曲時造成操作頻率與輻射效率下降，其中 輻射效率下降主要歸因於天線因彎曲而增加結構間之電容耦合，進而造成電磁能 量不易輻射而侷限於結構中; 此外，電容耦合亦造成天線等效共振電路中之電容 增加，進而造成天線共振頻率下降。在輻射場型方面，天線在基板彎曲時造成指 向性下降，尤其當天線基板彎曲成圓柱與橢圓柱時，輻射場型的零點變得不明顯， 天線之輻射特性近似於點源輻射。所設計之可繞式天線可應用於醫療用植入器 (medical implant device)、可穿戴式電腦系統(wearable computer system)，以及智慧型衣料(smart clothing)的研發The design and analysis of a planar, compact, and flexible zigzag dipole are presented. A flexible printed circuit board (FPCB), which is light, thin, and bendable,is exploited for antenna substrate design. The zigzag structure is used to realize a compact antenna design. The flexible zigzag dipole structure can be deformed into planar, parabolic, cylindrical, and elliptical forms through the molds made of rigid polyurethane. In this thesis, the parametric study regarding the impact of the structure deformation on the antenna radiation characteristics are presented, and the simulated results are verified by experimental demonstration. The simulated and experimental results show that the operating frequency and the radiation efficiency decrease owing to the structure deformation. Specifically, the decrease of the radiation efficiency is mainly attributed to the increase of capacitive coupling between the two zigzagged arms of the dipole, which leads to poor radiation from the antenna structure. In addition, the increase of the capacitive coupling corresponding to the increase of the capacitance in the antenna equivalent lumped circuit. Consequently, the resonant frequency of the dipole is down shifted. As for the radiation patterns, the structure deformation leads to the decrease of the antenna directivity. Technically, the deformation, especially for the cases in cylindrical, and elliptical forms, appears to convert the original directional radiation source into the omnidirectional one. The iii propose antenna can find applications in medical implant devices, wearable computer systems, and smart clothing. |
