本論文研究一個長方形柱體狀的超高頻(UHF)天線之優化設計，超高頻天線在此的功用為一個局部放電檢測系統的關鍵檢測元件，此元件以0.8mm厚的FR4基板(相對介電係數為4.4)來進行分析模擬、設計與實驗驗證。 超高頻天線的優化設計乃是以一個長方形單極當作初始結構，並將其細分成多個(例如10個)細長方形的金屬strip，且以strip的長度當作待決定變數；再將天線本體的接地面加以延伸，並使其為彎曲成一個薄柱狀型的天線結構，以達到縮小化的目的。 本論文的另一目的在測試不同優化過程(基於等差田口優化法)的設計效果，包括只使用響應表的結果來進行優化，或是比較響應表的結果與直交表實驗的結果，擇優來進行優化。經過測試的經驗顯示，後者比前者可以在較少的迭代次數找到最佳的數值結果，且其獲致的|S11|max 數值也都低於期望的-10dB以下，而尺寸也會比前者方法找到的來得更小。 This thesis investigates the optimization design of ultra high frequency (UHF) sensing antennas of rectangular cylinder shape. The UHF antenna functioning as a sensor is a key element of a partial discharge detection system. The element is assumed to reside on an FR4 substrate (relative permittivity power factor of 4.4) of thickness 0.8mm, while its simulation, design and experimental verification are carried out.
Optimal Design of the proposed UHF antenna start with a structure of rectangular monopole, which is subdivided into a plurality of (e.g., 10) rectangular thin metal strip, and the lengths of the strips serve as variables to be determined; In additions, the ground plane of the antenna is extended and bent to form an S-shape antenna structure for the purpose of downsizing.
Another objective of the thesis is to test the design outcomes of different optimization procedures (based on arithmetic Taguchi’s optimization method), which includes the use of the results from response table only for optimization, or through the comparison of the above results mentioned with those results of the orthogonal table; for the latter, the better one is chosen for optimization. Empirical tests show that the latter procedure can yield better numerical results with fewer iterations than the former did; and the attainable values of S11 are lower than -10dB expected, and the antenna size is smaller, too.