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題 名 | 陶瓷對衛星定位縮小化微帶天線之影響=The Influence of Ceramics on Compact Microstrip Antennas |
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作 者 | 楊證富; | 書刊名 | 筧橋學報 |
卷 期 | 6 1999.09[民88.09] |
頁 次 | 頁1-12 |
分類號 | 448.813 |
關鍵詞 | 陶瓷基板; 覆蓋層; 微帶天線; 全球定位系統; 圓極化; Ceramic substrate; Superstrate; Microstrip antenna; Ceramic; GPS; Circular polarization; |
語 文 | 中文(Chinese) |
中文摘要 | 第一主題:衛星定位陶瓷微帶天線的研製方法 本計畫主要將進行設計及研製應用於全球衛星定位系統( GPS; Global Positioning System )之右旋圓極化微帶天線。 天線(微帶金屬片)將以厚膜網版印刷在陶瓷基板上, 其操作中心頻率為 1.5754GHz。而天線形狀則採用(一)近似正方形結構。(二)正方形兩 對角截角結構。我們將首先以嚴密的全波理論分析設計此種微帶天線之長寬,並計算其操作 頻寬以及在頻寬範圍內之右旋圓極化特性。接著再進行實際之製作,量測其輸入阻抗、操作 頻寬( VSWR ≦ 2 )及輻射場型等天線特性,並與理論驗證。 各種不同介電常數及厚度之 陶瓷基板對天線之特性影響,將是研究的重點。 為了達到小型化的目的, 選擇介電常數為 26 的陶瓷基板將可以使天線大小約為 2.54 × 2.54cm. 在本項研究中,(一)近似正方形 結構:我們將利用調整矩形微帶天線的長寬比,使天線能夠同時激發水平及垂直兩方向之電 流,造成兩互相垂直之電波輻射,同時具有九十度之相位差,而得到圓極化波之輻射。另外 其饋入電路則選擇使用同軸線( coaxial feed )直接饋入於天線之對角線上。(二)正方 形兩對角截角結構:此種設計為圓極化波微帶天線之設計方法中,最為簡單的一種,非常適 合應用在 GPS 之接收天線系統上。 第二主題:陶瓷覆蓋層對縮小化微帶天線的增益方法 本計畫主要將進行設計陶瓷覆蓋層應用於對微帶天線的增益研究。由於微帶天線藉由短路可 以達到縮小為四分之一波長大小,縮小化是一種驅勢,但是縮小後增益必須經由主動放大器 來補償,由於主動放大器須要額外的直流電源相當不方便。因此本計畫中利用適當厚度的陶 瓷覆蓋層將有助於減少微帶天線上的表面洩漏波,以達到更高的輻射效率,也就是說陶瓷覆 蓋層相當於不須要額外的電源被動放大器。微帶天線藉由加在輻射金屬與接地間的晶片電阻 可以達到天線縮小和寬頻的效果,藉以改善微帶天線一般只有少於 2 %窄頻的特性。 此外 覆蓋層對圓形極化波增益也將實驗探討。在本項研究中,(一)覆蓋層厚度與相對介電常數 對增益的相關性。(二)基板相對介電常數對覆蓋層相對介電常數對增益的相關性。並且使 用 IE3D 模擬軟體分析天線輻射場型和增益。 |
英文摘要 | Subproject 1: Design and fabrication of GPS ceramic microstrip antenna This project is to design and fabricate the right-hand circularly polarized (RHCP) microstrip antenna applied to Global Positioning System. The microstrip patch will be screen printed on ceramic substrates and the central operating frequency is at 1575.4 GHz. The nearly square patch and square patch with diagonal perturbation will be used in this study. To design the aspect ratio of the nearly square patch, we will apply the fullwave approach to analyze the microstrip antenna. And the operation bandwidth and radiation pattern will also be calculated. Based on the theoretical prediction the microstrip antenna will be fabricated and measured. Effects of the ceramic substrates with various permittivities and thicknesses on the antenna characteristics will be the major topic of this study. In this investigation the circularly polarized radiation is obtained when the aspect ratio of the rectangular patch is about 1.002-1.03, depending on the substrate thickness and permittivity. In this case the antenna can excite two orthogonal modes with equal amplitude and phase quadrature, and circular polarization is then obtained. To excite the antenna the microstrip line is used which is fed on the diagonal of the nearly square patch. This kind of design is the simplest form to generate circular polarization and is very suitable for the GPS RHCP microstrip antenna design. Another structure with a square patch adequate cutted at the cross corner is also studied. Subproject 2: Studies of gain enhancement of miniature microstrip antenna loaded with ceramic superstrate This project will investigate in gain enhancement with the the high-permittivity ceramic superstrate loading. The chip-resistor loaded techniques have been shown to be very effective in the antenna size reduction and bandwidth broadness at some expense of the antenna gain. It is noted that a superstrate (cover) layer on the top of a microstrip antenna may significantly affect the radiation properties. If the substrate is thin enough, a superstrate layer may be used to eliminate surface-wave excitation, resulting in an radiation efficiency of 100%. In this study, by adding an adequate high-permittivity ceramic superstrate layer, the antenna gain of a chip-resistor-loaded patch antenna may be increased to be about the same level of a conventional patch antenna but with the miniature and broadband characteristics. With the simulation of IE3D software, we can find the rule of adequate superstrate thickness for maximun gain. |
本系統中英文摘要資訊取自各篇刊載內容。