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標題: | 平面式寬頻圓極化漏波天線與序列式旋轉饋入電路及其天線陣列應用 Planar Broadband Circularly Polarized Leaky-Wave Antennas and Sequential Rotation Feed for Array Applications |
作者: | Shih-Kai Lin 林士凱 |
指導教授: | 林怡成 |
關鍵字: | 寬頻,圓極化,漏波天線,序列式旋轉, broadband,circularly polarized,leaky-wave antenna,sequential rotation, |
出版年 : | 2012 |
學位: | 博士 |
摘要: | 本論文提出並實證了一系列的平面式寬頻圓極化漏波天線、序列式饋入電路以及數個序列式旋轉天線陣列。
最起始之天線形狀為一個圓形的槽孔,其中以一個扇形的金屬片做為干擾,使能量在耦合至槽孔上時,得以在兩側得到不同的邊界條件,其中一邊產生共振現象,用以匹配輸入阻抗,而另一側產生行進的漏波並且在正上方得到寬頻圓極化的輻射能量;接著結合指數曲線天線的概念,使得原先天線中沿著圓弧行進的漏波改為沿著一指數曲線行進,成功的改善了寬頻圓極化的特性;最後則提出了一個小型的指數型曲線槽孔天線,藉由不同特性的指數曲線,使得原先需要數個電氣波長長度的指數型曲線天線得以在小面積中實現,同時仍保持著良好的寬頻圓極化特性,而為了改善場型偏斜的問題以及單向輻射場型的實現,亦以此為基礎,提出了雙槽孔(dual-slot)以及添加平面反射板的設計。由實驗結果得知,這些天線都有著寬頻圓極化的表現,包含有10-dB返回損失、3-dB或6-dB的軸長比以及天線增益。 本論文中的序列式饋入電路整合四分之一波長的阻抗轉換器在序列式饋入電路必要的信號延遲線內,因此可以轉換任意天線阻抗至饋入電路的輸入端。也因此,本論文所提出之序列式饋入電路所佔面積小,可以容納天線陣列中天線元件間距調整的彈性。另由於幾何對稱的特性,此饋入電路也易於擴展至任意2N×2N的天線陣列。 在論文最後,結合前面章節所提出的寬頻圓極化漏波天線與序列式饋入電路,整合成序列式旋轉天線陣列並達到寬頻、高增益的圓極化特性。從實驗結果得知,2×2的序列式旋轉天線陣列的頻寬可達45%,其頻寬定義為同時滿足返回損失10-dB、軸長比3-dB以及半功率頻寬,天線增益最大值約為8.5 dBic。為了更高天線增益與更高的槽孔效率,我們另外設計了一個4×4的序列式旋轉天線陣列。此天線陣列的天線增益可達20.4 dBic,有效的槽孔效率為77.2%。 This dissertation presents a series of broadband leaky wave circularly polarized (CP) aperture antennas, the specific topology of sequential phase (SP) feeding network and the sequential rotation (SR) antenna arrays. The original design is composed of a circular aperture with a fan-shaped perturbation. The perturbation constructs the boundary conditions, thus the energy coupled to the aperture will split into two ways. The traveling wave propagating along the arc radiates in CP at broadside with broadband characteristic. By importing the concept of the exponential curve antenna, the traveling wave in the following antenna propagates along an exponential curve which enhances the performance of the CP features of the antenna. Finally, a compact antenna of exponentially curved slot as a radiator is realized. By the usage of different parameters of the exponential curves, the size is reduced from the traditional exponential antennas. Moreover, to overcome the beam tilt problem and to use the antenna in practical case, a dual-slot design with reflector is also proposed and realized. Verified by the experimental results, the presented antennas all perform broadband characteristics, including the 10-dB return loss, the 3-dB or the 6-dB axial ratio (AR), and the CP gain. The SP feed presented in this dissertation may transform the antenna impedance to the feed port impedance for arbitrary values due to the quarter wavelength transformers embedded in the designed delay line. Moreover, the SP feed only occupies a small area as to be accommodated in the array layouts with flexibility to adjust the antenna element spacing. Lastly, several SR antenna array designs which integrate the SP feed and the antennas presented in this dissertation are presented to achieve broadband and high gain CP performances. For 2x2 SR antenna array, the overlapped bandwidth of the achieves about 45%, under the criteria of 10-dB return loss, 3-dB AR, and 3-dB CP gain flatness, where the maximum gain is about 8.5 dBic. Another SR antenna array is composed of 4x4 antenna elements for high gain and high aperture efficiency, where a CP gain of 20.4 dBic and an aperture efficiency of 77.2% are achieved. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/64420 |
全文授權: | 有償授權 |
顯示於系所單位: | 電信工程學研究所 |
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