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Title: | 應用於低軌衛星通訊之寬頻左右圓極化可切換之天線單元及子陣列設計 Design of Broadband Right- and Left-Handed Circular Polarization-Switchable Antenna Element and Sub-Array for Low Earth Orbit Satellite Communication |
Authors: | 蔡昀廷 Yun-Ting Tsai |
Advisor: | 陳士元 Shih-Yuan Chen |
Keyword: | 軸比頻寬,耦合,極化可切換,序列式旋轉饋入,U形開槽貼片天線, axial-ratio bandwidth,mutual couplings,polarization agility,sequential rotation,U-slot patch antennas, |
Publication Year : | 2023 |
Degree: | 碩士 |
Abstract: | 本論文首先提出基於三個模態之寬頻圓極化天線單元、據此設計寬頻圓極化可切換之天線單元、並提出一個可減緩陣列內部耦合所造成效能下降的子陣列設計流程,以及為不同應用場景所設計,基於通解型序列式旋轉饋入的天線陣列。
首先,本論文提出的寬頻圓極化天線單元為具有U形開槽與四個截角的矩形貼片天線,由於其軸比值頻率響應具有兩個低點,此天線的軸比頻寬從傳統U形開槽貼片天線的5%增加至14.6%。吾人利用特徵模態分析發現此設計因激發出第三個主模態,形成一個有別於傳統的三模態工作模式,貢獻了此軸比頻寬。 此外,吾人在此設計上加入兩顆切換用的PIN二極體,以實現極化可切換之特性並維持原天線尺寸。這兩顆PIN二極體使U形開槽具有可重構性。透過適當的設計,隔離射頻和直流訊號用的元件與開槽對於模態分佈之干擾皆被抑制。所設計的天線可以在不增加尺寸和複雜度的情況下在左手和右手圓極化之間切換,並具有12.6%的可用頻寬。 由於原本天線的寬頻圓極化特性在擴展成大陣列後會因為陣列內部耦合而有大幅度的失真,本論文提供一個建立於耦合分析的子陣列設計流程,減緩耦合在大型陣列中與掃描波束時的影響。最後,在大型陣列的設計,除了傳統直接複製多個子陣列的方式,本文另外提出三種基於通解型序列式旋轉饋入的天線陣列設計,為不同場景提供更高的寬邊輻射增益、波束掃描範圍內更穩定的軸比頻寬,或在寬邊增益和波束掃描到其他角度的增益損失之間進行權衡。 In this thesis, we proposed a tri-mode broadband circularly-polarized (CP) antenna element, broadband circular polarization-switchable antennas based on the proposed design, a sub-array design flow mitigating degradations due to mutual coupling, and novel extensive antenna arrays based on generalized sequential rotation feeding technique for various application scenarios. Firstly, thanks to the two dips in the AR response, the proposed antenna element, a U-slot patch antenna with four truncated corners, shows a 14.6% axial-ratio (AR) bandwidth, significantly improved from the 5% AR bandwidth of a traditional U-slot patch antenna. It is shown by characteristic mode analysis that the proper excitation of the third dominant mode results in a unique tri-mode CP operation, leading to a wide bandwidth. Moreover, inserting two PIN diodes transforms the antenna into a polarization-agile one. The two PIN diodes enable the U-slot to be reconfigurable. The effect on the modal current distributions can be mitigated by properly designing the associated bias circuit, including the slits and the SMD components. The designed antenna can switch between left-handed and right-handed CP with a 12.6% usable bandwidth without increasing the size and complexity. In addition, we also provide a sub-array design flow that mitigates the distortions due to coupling regarding an array with considerable elements and beam scanning. Finally, besides direct subarray duplication for an extensive array, three alternative designs based on the generalized sequential rotation feeding technique are proposed in this thesis, providing a higher broadside gain, a more stable AR bandwidth during beam scanning, or trading off between broadside gain and scanning gain loss for different scenarios. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/90615 |
DOI: | 10.6342/NTU202301854 |
Fulltext Rights: | 同意授權(全球公開) |
Appears in Collections: | 電信工程學研究所 |
Files in This Item:
File | Size | Format | |
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ntu-111-2.pdf Until 2028-07-25 | 10.32 MB | Adobe PDF |
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