緊密的多接收多發送天線系統於無線區域網路系統的應用

Abstract

本論文提出三個整合多天線於小面積的系統。首先介紹的第一個天線系統，它整合了兩支天線，適用時間分集或是場型分集，第一支天線是Sigma形單極天線，第二支天線是由W形單極天線所構成的系統，主要是操作在2.4GHz頻段，此系統頻寬不錯，且輻射場形也有達到全向性，天線間的信號干擾也可達到要求的-10dB以下。接下來介紹第二個天線系統，主要是由方形環狀單極天線系統構成，此架構整合了三支天線，兩支天線負責兩邊的輻射，中間的天線負責往前的輻射以補另外兩支天線往前輻射的不足，且操作頻率在2.4、4.9、5.2、5.8GHz，符合全頻段的需求，輻射場型在全頻段各方向有互補的效果，但其中有兩支天線的信號干擾略高，約在-8.5dB。接下來要繼續介紹第三個系統，由四支天線所構成的緊密多接收多發送（MIMO）天線系統，這裡會提出數種天線設計架構並比較各種設計的優缺點，我們會舉幾個實作的天線系統來做例子。天線間信號干擾的效應就是研究的重點，除了造成基頻信號處理的困難外，也會造成天線間的破壞性干涉使得增益降低，量測的結果會說明信號干擾效應造成的問題，量測結果和心得會討論。

In this thesis, three compact antenna systems are proposed. In the first system, two antennas are located in the front side of PC card, and it is suitable for time diversity and pattern diversity application. It operates at 2.4GHz band and has wide bandwidth, omni-directional radiation pattern. One of the two antennas was designed to have Sigma shape and another was in W shape. And the interference between antennas is below the required -10dB. The second system is mainly composed by three square-loop ring antennas. Two of these antennas radiate to left and right side of the PC card, and the third antenna radiates forward to compensate the insufficient radiation. Each of these antennas covers the frequency bands of 2.4, 4.9, 5.2, 5.8GHz. In addition, the radiation pattern of these antennas is complementary in all directions to realize pattern diversity. But the highest interference between these antennas is about -8.5dB. The last antenna system is composed by four multi-band antennas to form a compact MIMO antenna system. We will propose several frameworks to design compact MIMO antenna system and compare their advantages and disadvantages. Then we will take some experimental examples to introduce these frameworks. The interferential effect among antennas is the researching key point. It causes not only signal process at baseband difficult but also destructive interference to radiation pattern. The interferential effect is discussed in the measured results.