[[alternative]]Design of the satellite Ku-band CP array antennas and its initial study of optimization

碩士[[abstract]]本論文的目的是在設計一使用於Ku頻帶衛星的圓極化陣列天線，微波頻段的Ku頻帶範圍是12GHz~18GHz，本論文主要探討的是用於固定式衛星服務及衛星廣播服務11.45~12.75GHz之頻率範圍的圓極化陣列天線，首先設計出一符合圓極化Ku頻帶衛星頻帶要求之單一天線元件，此單一元件達到寬頻、圓極化的特性外，更要有高增益(高指向性)、低旁瓣及隔離度的基本要求。 本論文提出的衛星圓極化陣列天線結構為以簡單的槽孔耦合patch天線(Aperture Coupling Patch Antenna)為基礎，此天線具有三層金屬結構，上層為方形patch輻射體之所在，中層為接地面(Ground Plane) 金屬，也是耦合槽孔之所在，下層金屬為50Ω饋入線之所在，當槽孔1和槽孔2的饋入線的相位相差90度即可產生圓極化輻射，另外，為了減少背向輻射又加上另一金屬接地面形成四層金屬的結構。 我們發現令激發槽孔位在patch的角會比位在patch的邊有更好的隔離度，並於後續結構中採用。另外，針對饋入網路，考慮頻寬的因素，吾人選用威爾金森(Wilkinson)功率分配器來做為訊號功率饋入的分配元件。為了考慮饋入網路走線之間彼此的耦合效應，它的激發路徑也是必須要經過精密的調整。我們探討了2X1及2X2陣列的模擬特性，並實作了2X2陣列的原型，模擬和量測結果非常一致。 接著，本論文進一步將遺傳演算法應用於圓極化陣列天線（Antenna Arrays）的最佳化，目標在調控激發相位使得圓極化陣列天線可在空間座標中進行波束掃描，為了在掃描主波束的過程中維持圓極化的特性，並達到較低的旁瓣位準(SLL)，必須將其鄰近元件的耦合效應納入。為此，吾人得事先計算取得整個天線陣列環境（至少包含鄰近元件）中的單一天線元件在單阜（不是雙阜）饋入下的輻射特性，吾人利用全波模擬軟體來模擬2X2陣列天線在某一單阜獨自激發的情況下的輻射遠場rE，包括各角度的數據之收集，以作為GA演算程式做進行個別阜的激發相位調整時的輻射遠場更新之用。最後，針對2X2陣列天線的激發相位進行優化設計，但得先選擇適當的條件式與權重：由於是圓極化的陣列天線，故在波束掃描過程中，高增益（高指向性）、低旁瓣位準(SLL)以及低軸比等特性的維持都被納入搜尋條件。再藉由遺傳演算法來搜尋最佳解，以計算出掃瞄各角度所需的激發值相位列表，並將GA最佳化的結果與模擬軟體的數據進行的比對，結果顯示兩者之間的準確度及一致性極高，兩者誤差比約在1%以內。[[abstract]]The purpose of this thesis is to design a Ku-band circular polarization array for satellite application. Ku-band microwave frequency ranges from 12GHz to 18GHz in general. The objective of this thesis is to explore the circular polarization array antenna for fixed satellite services and satellite broadcasting services covering 11.45 ~ 12.75GHz frequency range. At first, one need to design a single antenna element with circular polarization that meet Ku-band satellite bandwidth requirements. The single antenna element need to achieve broadband characteristics of circular polarization, but also have high isolation. This thesis presents an array of circular polarization satellite antenna, of which the structure is based on a simple slot-coupled patch antenna. The patch antenna has three matellic layers, of which the upper layer is where a square patch radiator resides. Meanwhile, the middle layer is the metallic ground plane, where the coupling slots are etched, and the lower layer is intended for the 50Ω feed line and/or feeding network. When the feed line for slot 1 and slot 2, respectively, exhibits 90-degree phase difference the circular polarization of radiation can be generated. In addition, in order to reduce the backscattered radiation another metal surface is added to form a four-layer metallic structure. We found that putting the excitation slot at the corner of the patch can improve the isolation as compared with putting the excitation slot at the edge of the patch. Thus the structure with excitation slot being at the corner of the patch is adopted for the successive investigation. In addition, for the feeding network the Wilkinson power splitter is used to feed input signal power regarding the frequency bandwidth. Taking into account of the coupling effect between the feed lines of near paths, careful adjustment for the path length is necessary. We have examined the simulated characteristics of the 2X1 and 2X2 arrays, and the prototype of the 2X2 array is fabricated and measured. The simulation and measurement results are found in very good agreement. Then, in this thesis the genetic algorithm is applied to further optimize the design for the circular polarization array antenna. The objective is to scan the main beam by suitable adjustments of the phase of the excitation current. During the course of scanning the characteristics of circular polarization must be maintained, meanwhile, the sidelobe level (SLL) is kept low, for which the coupling effect between the antenna elements must be took into account. To accomplish this, we have to calculate in advance the radiated E fields of the entire antenna array (at least including the neighboring components) with only a single antenna element being excited. The full-wave simulation software is employed to simulate the the 2X2 array antenna as mentioned. The far zone E fields rE of all the angles (up to one degree resolution) are obtained and saved for successive optimization using GA algorithm. In GA, the far zone E fields must be updated for different phase adjustments of the excitation current. Finally, for the optimal excitation phase searching for the 2X2 phase array, one must first select the appropriate optimization conditions and weights: as a circular polarization array antenna is considered, the conditions of high-gain, low sidelobe level (SLL) and low axial ratio are included into the searching fitness criteria. Then through the genetic algorithm the optimal solution to achieve the required scanning angle can be obtained, and the list of the excitation phases of the current is calculated and saved for practical usage. The results of GA optimization are compared with the simulation results by software, and the results show very good accuracy and consistency with error less than 1%[[tableofcontents]]目錄 中文摘要...........................................II 英文摘要...........................................V 第一章 序論 ...................................... 1 1.1概述 .......................................... 1 1.2 研究動機 ..................................... 22 1.3 研究內容簡介 ................................. 24 第二章 槽孔式耦合圓極化平面天線 .................. 25 2.1 前言 ......................................... 25 2.2 微帶天線的優點與缺點 ......................... 26 2.3 微帶天線輻射原理 ............................. 27 2.4饋入激發的方式 ................................ 31 2.5 反射金屬板(Metal Reflector) .................. 34 2.6等效電路(Equivalent Circuit) .................. 35 第三章 陣列天線的模擬與饋入網絡 .................. 39 3.1 整體天線的結構與實驗構思 ..................... 39 3.2 單一圓極化天線設計分析 ....................... 43 3.3威爾金森功率分配器(Wilkinson power divider) ... 60 3.3.1結合威爾金森功率分配器的單一菱形天線 ........ 64 3.3.2陣列天線與饋入網路 .......................... 72 第四章 量測與分析 ................................ 81 4.1實體製作 ...................................... 81 4.2遺傳演算法進行相位陣列天線最佳化設計 .......... 89 第五章 結論 ...................................... 95 圖目錄 圖一、衛星的即時移動影音通訊的示意圖...............1 圖二、遺傳演算法的流程圖示.........................5 圖三、目標條件式架構...............................6 圖四、天線陣列示意圖...............................7 圖四、天線陣列示意圖(續)...........................8 圖五、一個二維矩形天線陣列的幾何結構示意圖.........10 圖六、Cmnpq 描述互耦合(mutual coupling)的效應......12 圖七、各種陣列天線的型態...........................14 圖八、蝴蝶型式(bow-tie)天線........................15 圖九、梯狀型態的天線...............................16 圖十、2D輻射場形圖 .................................16 圖十一、(a)小環金屬線條天線以及軸比特性參數........17 圖十一、(b)菱形狀金屬線條天線以及軸比特性參數......17 圖十一、(c)菱形狀金屬線條天線以及軸比特性參數......18 圖十二、(a)特殊材質鈦酸鍶鋇結構圖..................19 圖十二、(b)特殊材質鈦酸鍶鋇位置移動圖示............19 圖十二、(C)特殊材質鈦酸鍶鋇各項圖表................20 圖十三、微帶天線示意圖.............................25 圖十四、平面式微帶天線各符號表示...................27 圖十五、平面式微帶天線(a)為立體圖(b)為側邊圖，圖(c)為俯視圖.................................................28 圖十六、平面式微帶天線(a)直接饋入(Direct feed) (b)同軸(Coaxial) ..........................................31 圖十七、孔隙天線...................................33 圖十八、孔隙天線各介質層簡述.......................34 圖十九、正規化後的等相位天線雷達圖與示意圖.........35 圖二十、等效電路 (a)側圖(Side View) (b)俯視圖(Top View) ...................................................35 圖二十一、通用的網路模型...........................36 圖二十二、電場在孔隙中分佈的現象...................37 圖二十三、阻抗匹配等比關係.........................37 圖二十四、天線陣列之組成元件的概略示意圖...........42 圖二十五、單一天線元件初始架構的尺寸及外觀.........44 圖二十六、初始架構天線元件的（a）S參數、(b)2D輻射圖及（c）軸比及(d)Port1與Port2相差(Phase)90度激發的電流圖。...47 圖二十七、修正初始架構天線元件的（a）結構（b）S參數及(c)軸比.................................................50 圖二十八、輻射體位置修正為菱形.....................50 圖二十九、(a)菱形的天線結構之s參數特性.............51 圖二十九、(b)菱形的天線結構之AR....................51 圖三十、修改菱形天線結構的槽孔設計.................52 圖三十一、(a)修改菱形天線槽孔後的單一天線元件之S參數 ...................................................53 圖三十一、(b)修改菱形天線槽孔後的單一天線元件之AR參數 ...................................................53 圖三十一、(c)修改菱形天線槽孔後的單一天線元ZX-Plane ...................................................54 圖三十一、(d)修改菱形天線槽孔後的單一天線元ZY-Plane ...................................................54 圖三十二、(a)HFSS上菱形天線輻射導體的尺寸..........55 圖三十二、(b)菱形天線厚度尺寸......................55 圖三十二、(c)HFSS上的菱形天線尺寸..................56 圖三十三、(a)菱形天線的S參數模擬結果...............56 圖三十三、(b)菱形天線的AR模擬結果..................57 圖三十三、(c)菱形天線的隔離度模擬結果..............57 圖三十三、(d)ZY-Plane的模擬輻射特性................58 圖三十三、(e)ZX-Plane的模擬輻射特性................58 圖三十三、(f)XY-Plane的模擬輻射特性................59 圖三十四、威爾金森功率分配器.......................60 圖三十五、威爾金森功率分配器在HFSS上模擬...........62 圖三十六、威爾金森功率分配器的S參數................63 圖三十七、(a)結合菱形天線與威爾金森功率分配器......64 圖三十七、(b)結合菱形天線與威爾金森功率分配器後的S參數 ...................................................65 圖三十七、(c)結合菱形天線與威爾金森功率分配器的AR..65 圖三十七、(d)結合菱形天線與威爾金森功率分配器ZX-Plane ...................................................66 圖三十七、(e)結合菱形天線與威爾金森功率分配器ZY-Plane ...................................................66 圖三十七、(f)結合菱形天線與威爾金森功率分配器XY-Plane ...................................................67 圖三十七、(g)結合菱形天線與威爾金森功率分配器的激發電流分佈圖.................................................67 圖三十八、加入金屬背板.............................68 圖三十九、(a)加入金屬背板後的S參數.................69 圖三十九、(b)加入金屬背板後的AR....................69 圖三十九、(c)ZX-Plane的模擬輻射特性................70 圖三十九、(d)ZY-Plane的模擬輻射特性................70 圖三十九、(e)XY-Plane的模擬輻射特性................71 圖四十、2 x 1天線陣列結構圖........................72 圖四十一、(a) 2 x 1天線陣列的S參數.................73 圖四十一、(b) 2 x 1天線陣列的軸比..................73 圖四十一、(c) 2 x 1天線陣列ZX-Plane的模擬輻射特性..74 圖四十一、(d) 2 x 1天線陣列ZY-Plane的模擬輻射特性..74 圖四十一、(e) 2 x 1天線陣列XY-Plane的模擬輻射特性..75 圖四十二、(a) 2 x 1天線陣列的電流分佈圖............75 圖四十二、(b) 2 x 1天線陣列的電流分佈及相量圖......76 圖四十三、(a)七個威爾金森功率分配器形成的2 x 2天線陣列之饋入網路...............................................76 圖四十三、(b) 2 x 2天線陣列的S參數.................77 圖四十三、(c) 2 x 2天線陣列的AR....................78 圖四十三、(d) 2 x 2天線陣列ZX-Plane的模擬輻射特性..78 圖四十三、(e) 2 x 2天線陣列ZY-Plane的模擬輻射特性..79 圖四十三、(f) 2 x 2天線陣列XY-Plane的模擬輻射特性..79 圖四十三、(g)七個威爾金森功率分配器加2 x 2天線陣列的電流分佈.................................................79 圖四十四、2x2天線陣列饋入網路系統的結構尺寸........80 圖四十五、(a)威爾金森功率分配器實體圖..............82 圖四十五、(b) 2x2天線陣列槽孔實體圖................82 圖四十五、(c) 2x2天線陣列輻射體實體圖..............83 圖四十五、(d) 2x2天線陣列反射板實體圖..............83 圖四十六、2x2天線陣列各種板材的材料圖示............84 圖四十七、以塑膠螺絲固定的2x2陣列天線原型..........85 圖四十八、(a) 2x2天線陣列的駐波比..................86 圖四十八、(b) 2x2天線陣列的S參數...................86 圖四十九、(a) 2x2天線陣列ZX-Plane量測與模擬的2D輻射場形比較圖.................................................87 圖四十九、(b) 2x2天線陣列ZY-Plane量測與模擬的2D輻射場形比較圖.................................................87 圖四十九、(c) 2x2天線陣列XY-Plane量測與模擬的2D輻射場形比較圖.................................................88 圖四十九、(d) 2x2天線陣列ZX-Plane量測與模擬的HPBW束寬比較圖.................................................88 圖五十、為2X2陣列天線各點激發阜的示意圖............91 圖五十一、為(Case1)2D的場形圖......................93 圖五十二、為(Case1)3D的立體圖......................93 圖五十三、為(Case2)2D的場形圖......................94 圖五十四、為(Case2)3D的立體圖......................94 表目錄 表一、威爾金森功率分配器的插入損耗.................61 表二、模擬與實測之間的差異表.......................81 表三、主波束在 且 (Case1)，由GA最佳化的數值與HFSS數值的比較(Case1)GA最佳化後所得數值與HFSS數值的比較表........91 表四、主波束在 且 (Case2)，由GA最佳化後的數值與HFSS數值的比較(Case2)GA最佳化後所得數值與HFSS數值的比較表......92[[note]]學號: 696440055, 學年度: 9