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標題: | 天線能量場型之性能分析及其應用 Performance Analysis of Antenna Energy Pattern and Its Applications |
作者: | Chao-Hsiang Liao 廖兆祥 |
指導教授: | 許博文(Powen Hsu),張道治(Dau-Chyrh Chang) |
關鍵字: | 能量場型,能量增益,超寬頻陣列,微波影像, energy pattern,energy gain,UWB array,microwave imaging, |
出版年 : | 2010 |
學位: | 博士 |
摘要: | 一般而言,天線場型量測都是在頻域下所測量得到功率場型,容易描述窄頻通訊系統的天線場型,但是在超寬頻通訊系統中,由於過多的功率場型似乎不容易描述天線之特性,也就是說傳統的頻域量測方式較適合來描述窄頻帶的天線特性,提供窄頻帶通訊系統使用,因此本論文提出使用能量觀點來描述超寬頻通訊系統之天線性能,也是就能量場型、能量增益、以及能量效率等定義,並且使用八朩天線、多波束智慧型天線陣列、超寬頻共面波導饋入領結開槽天線、超寬頻梳型緩變槽孔天線、以及由四支超寬頻梳型緩變槽孔天線單元組成之三種不同間距的超寬頻天線陣列,陣列天線的天線單元間距分別為2.5公分、8.5公分、及18公分等天線來比較能量場型與功率場型的差異,並藉由能量場型來分析線性及非線性間隔的天線單元之陣列來作比較及探討。
第二部份將使用時間延遲技術發展超寬頻天線陣列達到波束掃瞄之功能,並提出時域超寬頻天線陣列場型公式,使用天線單元間距為2.5公分、8.5公分、18公分等天線陣列且具有波束掃瞄20度的掃瞄功能來驗證所提出的理論公式。 最後使用天線單元間距為18公分的大孔徑面積陣列天線應用於微波影像,由於超寬頻天線陣列所輸出的波形可以有效的改善微波影像的解析度,因此使用寬頻雙脊喇叭天線為發射天線,接收天線則使用超寬頻天線陣列以及結合脈衝時域量測系統來構成真實波束雷達影像系統,此系統將接收到的時域訊號使用時間延遲與合成演算法來達成微波成像,並使用幾個鋁罐的例子來驗證此系統的解析度,相較於傳統收發天線都是使用寬頻喇叭天線的微波成像結果,由結果發現微波成像的解析度確實有提升。 Power patterns in the frequency domain are usually used to describe the antenna performance in narrowband communication systems; however, they are not sufficient for ultra wideband (UWB) antennas in wideband communication systems. In this dissertation, energy pattern, energy gain, and energy efficiency are introduced and used to describe the performance of UWB antennas and arrays. Numerical simulations and measurements are used to demonstrate the difference between power patterns and energy patterns for Yagi-Uda antenna, four beams smart antenna array, UWB CPW–fed bow-tie slot antenna, UWB comb taper slot antenna, and four-element UWB comb taper slot antenna array with element spacings of 2.5, 8.5, and 18 cm. The four-element UWB array system with uniform and non-uniform element spacing is analyzed by energy pattern. Second, a beam scanning technique is developed with a time delay for UWB arrays. In addition, a formulation of the time domain array factor for UWB antenna arrays is presented. An UWB comb taper slot antenna array with large element spacing and impulse excitation are studied and four-element UWB linear array systems with element spacings of 2.5, 8.5, and 18 cm in the broadside direction and 20 degree scanning are implemented. Finally, the four-element UWB comb taper slot antenna array with 18 cm element spacing is used for real beam radar imaging, the UWB array waveform is an effective way of improving the resolution for microwave imaging. A wideband double ridge horn antenna is used as the transmitting antenna, the above developed large aperture UWB array is used as the receiving antenna. The transmitting antenna and the receiving antenna are combined with impulse time domain measurement system to achieve real beam radar imaging. The receiving impulse signals at various positions are processed by the time delay and sum algorithm. The examples of several aluminum cans will be verified in the resolution of microwave image and compared with transmitting and receiving antennas are using wideband double ridge horn antenna. The results of real beam radar imaging from both simulation and experiment are well agreed. The cross range resolution of UWB antenna array is better than single wideband double ridge horn antenna due to the beam width of UWB array is narrower. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/48727 |
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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