臺灣博碩士論文加值系統

本研究旨在開發一種適用於固定翼無人機的柔性微帶天線，以實現雙頻應用。我們提出了一種新的設計技術，使用成本低廉的PVC基板，該基板輕巧、柔軟且具有良好的氣動特性。在實際原型製作後，該天線能夠在GPS L1和IEEE 802.11頻率上工作，並與模擬結果進行了比較。通過對不同彎曲半徑的天線進行參數研究，我們討論了天線發展的不同階段。第一個設計中使用的阻抗匹配方法是通過將單個馈源連接到傾斜的矩形貼片的相對側，生成90度的相位差。這種結構能夠產生右旋圓極化，對於GPS接收到全功率的信號非常重要，同時引入了正交支線以改善WLAN通信的匹配條件。第二個結構是第一個原型的連續設計，包括在基板上添加一個額外的氣隙層以改善增益特性。我們研究和驗證了兩種原型的輻射特性和增益效率。此外，我們還通過在不同攻角下進行模擬，評估了其氣動性能。

The current research aims to develop a conformal microstrip patch antenna that can be embedded on a fixed wing UAV for dual band application. A new design technique is presented using a low-cost PVC substrate which is light-weight, flexible with good aerodynamic characteristics. After the fabrication of actual prototype, it is capable to work at GPS L1 and IEEE 802.11 frequencies which was compared with the simulation results. Parametric studies have been done by conforming the antenna with different bend radius and different stage of development of the antenna has been discussed. The impedance matching method shown in the first design has been used by connecting dual-feed line to the opposite sides of the tilted rectangular patch which generates a 90-degree phase difference. This structure is capable of generating a right-hand circular polarization which is very important for GPS to receive signals with full power, whereas orthogonal stubs were introduced to improve the matching conditions for WLAN communications. The second structure is a successive design of the first prototype which includes an additional air gap layer over the substrate to improve the gain characteristics. The radiation characteristics and gain efficiencies for both the prototypes have been studied and validated. Moreover, aerodynamic performance has also been carried out by simulating at different angle of attacks.

Chinese Abstract......i
English Abstract......iii
Acknowledgement......v
Table of contents......vi
List of tables......viii
List of figures......ix
Symbols......xi
Chapter-1......1
1.1 Research objective......1
1.2 Dual band antenna design......
1.3 Working frequencies......2
1.3.1 GPS L1 carrier......2
1.3.2 Free space path loss......2
1.3.3 IEEE 802.11 (WLAN)......4
1.3.4 UAV module testing (WLAN)......5
1.4 Chapter overview......7
Chapter-2 Fundamentals of microstrip patch antenna......8
2.1 Types of microstrip feed techniques......8
2.1.1 Co-axial probe feed......8
2.1.2 Microstrip line feed......8
2.1.3 Aperture coupled feed......8
2.1.4 Proximity coupled feed......8
2.2 Radiation pattern......9
2.3 Gain......10
2.4 Polarization......10
2.4.1 Linear polarization......10
2.4.2 Circular polarization......10
2.5 Slots antenna......12
2.5.1 Literature review......12
Chapter-3 Dual band conformal antenna analysis......14
3.1Design principles......14
3.2 Stages of patch design......17
3.2.1 Effects on radiation efficiencies......20
3.2.2 Dual-feed analysis......21
3.2.3 Slits and orthogonal stubs analysis Linear polarization......28
3.3 Conformal design......33
3.3.1 Implementation......33
3.4 Antenna measurements......36
3.4.1 Gain......36
3.4.2 Radiation pattern......37
3.5 Subsequent fabricated prototype......42
Chapter-4 Aerodynamic effects on the embedded antenna......50
4.1 Geometry model......50
4.1.1 Mesh conditions......51
4.1.2 Grid independence study......52
4.2 Turbulent models......53
4.2.1 Navier Stokes equation......53
4.2.2 Spalart-almaras equation......53
4.3 An experimental study on antenna fairings......54
4.4 Performance at different angle of attacks of the regular airfoil......55
4.4.1 Pressure and velocity analysis......56
4.4.2 Streamline analysis......59
Chapter-5 Conclusion......62
5.1 Conclusion......62
5.2 Future work......63
References......64
Extended Abstract......67

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