2006-09-012024-05-16https://scholars.lib.ntu.edu.tw/handle/123456789/668714摘要：近年來，在衛星通訊、點對點或點對多點之高階無線通訊應用上，系統端對於天線之增益需求若渴。然而，峰值增益高於20、30dBi之指向性天線已無法以單一天線單元之形式達成。為了提高天線增益，較常使用的設計方法有三種：一為設計成天線陣列，也就是以多個天線單元組成之陣列來達到所需之增益，由於陣列中的各個天線單元往往會互相耦合，加上天線單元數目的增加，提高饋入傳輸線的路徑長度及功率損耗，造成該陣列之輻射效率不佳，進而限制了天線增益。其二為採用反射面聚焦的方式，也就是常見的碟形天線，但其製作及機械加工難度較高，且笨重不具機動性。最後則是結合光學透鏡與微波天線的方式，以光學的折射原理將饋入天線的主波束聚焦，進而提高天線增益。近來有人提出以一特殊形狀之介電材質作為透鏡，將饋入天線單元之輻射場有效聚焦，吾人稱之為介質透鏡天線。 由於介質透鏡天線之結構特殊且其尺寸往往為操作頻率下波長的數倍，目前為止僅有極少數之電磁模擬軟體能有效地針對介質透鏡天線進行分析與設計。本計畫首先將對介質透鏡天線進行分析，提出簡化的計算方法以利介質透鏡曲面之設計，並將實作一介質透鏡天線，並使用共面波導饋入之平面天線作為其饋入結構，<br> Abstract: In recent advanced applications, such as the satellite communications, point-to-point or point-to-multipoint wireless communications, higher antenna gains become more and more critical in the design of a transceiver module. However, it is understood that one single element antenna can never provide peak antenna gains as high as 20, 30dBi or even higher. In general, there are three major methods to increase the antenna gain. One is to design in the form of an antenna array, in which multiple antenna elements are integrated together. However, the power radiated from the antenna elements in an array inevitably will couple between each other, and the increasing number of antenna elements will lengthen the feeding transmission lines and thus increase the feedline losses. These factors hugely restrict the increase in antenna gains by means of an array. Another method is the use of reflectors to shape the mainbeam of a feeding antenna. At microwave frequencies, the paraboloid-shaped reflector antenna is perhaps the most well-known and widely used high-gain antenna for satellite communications. However, the difficulties in fabrication of reflector antennas make them expensive and not practical in many applications. In addition, the reflectors are very heavy. The last method, in which the refraction phenomenon in optics is applied to focus the electromagnetic waves, is the use of dielectric lenses. They are the so-called dielectric lens antennas. Recently, a specified surface of the dielectric lens has been proved to be able to efficiently sharpen the mainbeam in the far field. The dielectric lens antenna is composed of two parts, namely the well-shaped dielectric lens and a feeding antenna. Due to the electrically very large dimensions of the dielectric lens antennas, there is only little commercial software suitable for us to analyze and design with. In the current project, we will try to analyze the dielectric lens antenna and give a simple and precise method for the future design of the dielectric lens. The general design guidelines of a dielectric lens antenna will be given. Also, in the following year, we will design, implement, and test a novel dielectric lens antenna, in which we will utilize a coplanar waveguide-fed printed antenna as the feeding antenna, to verify the proposed design method.共面波導介質透鏡天線方向性天線高增益天線coplanar waveguidesdielectric lens antennasdirectional antennashigh-gain antennas