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    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/35784


    Title: 無線USB裝置使用之平面式縮小化超寬頻單極天線設計
    Other Titles: Design of a planar ultra-wideband miniature monopole antenna for wireless USB dongle devices
    Authors: 張祐嘉;Chang, Yu-chia
    Contributors: 淡江大學電機工程學系碩士在職專班
    丘建青;Chiu, Chien-ching
    Keywords: 超寬頻;單極天線;Ultra-Wideband;monopole antenna;USB Dongle
    Date: 2009
    Issue Date: 2010-01-11 07:08:59 (UTC+8)
    Abstract: 超寬頻(Ultra-Wideband, UWB) 技術,最早起源於西元1970年代,應用於軍方國防部門雷達通訊系統。隨著近年來無線通訊的傳輸需求從聲音、數據、影像到現今的多媒體應用,無線傳輸速度需求日益增大。隨著西元2002年2月14日美國聯邦通信委員會FCC(Federal Communication Commission)開放原先軍方國防部門所使用超寬頻技術,超寬頻通訊技術開始使用於消費性(Consumer)電子產品上。
    無線超寬系統的主要關鍵技術之一在設計一輕巧(Compact)、寬頻且全向性的天線,本研究針對全平面式的結構,採用厚0.4mm的FR4基板,以相對介電係數(Relative Permittivity)為4.4,Dielectric Loss Tangent為0.02,來進行模擬並和實驗相驗證,設計一符合3GHz ~ 5GHz UWB頻帶全平面式微帶單極天線,並進一步將此一全平面式天線縮小化與結構簡單化,使其降低生產成本與更易實際製作於印刷電路整合。
    在全平面式超寬頻單極天線結構的縮小化設計及增加天線頻寬上提出兩種新的設計技巧:其一是以天線初始結構,設計底部半圓形單極輻射體(Semi-Circular Base)並且加上對稱縫隙(Slit) 的形狀以達到天線縮小化目的,進而發現除了控制天線接地面(Ground Plane)和單極輻射體(Radiator)間隙,可改變天線虛部阻抗電容與電感性外,以單極輻射體增加縫隙(Slit)方式,可在不增加天線整體尺寸前提下,亦可調整天線虛部阻抗電容與電感性;其二則設計一接地面對稱寄生(Parasitic)架構,使天線同時達成寬頻匹配及縮小化的目的。經模擬與實測驗證,天線面積可縮小達33%。
    為了考慮到實際製作與與降低生產成本,除本研究天線結構為全平面結構外,另提出一天線簡化結構,其寬頻匹配特性仍維持3GHz ~ 5GHz UWB頻段。得到簡化結構後,本研究進一步藉由天線接地長度的縮短,探討天線尺寸的縮小極限,雖然天線匹配隨著接地面長度縮短而劣化,但若搭配應用本研究所提出之增加縫隙(Slit)結構方法,可改善其接地面長度縮短的劣化影響,進而達到寬頻匹配特性。
    考慮到H-plane上的場型維持全方向(Omni-Directional)輻射場型特性,本論文所提出增加縫隙(Slit)與寄生(Parasitic) 架構均為對稱性結構,其實測結果顯示其H-plane上的全方向(Omni-Directional)輻射場型特性確實非常良好。
    Ultra-wideband technology brings the convenience and mobility of wireless communications to high-speed interconnects in devices throughout the digital home and office. Designed for low-power, short-range, wireless personal area networks (WPANs), UWB is the leading technology for freeing people from wires, enabling wireless connection of multiple devices for transmission of video, audio and other high-bandwidth data.
    Nowadays, one of major key technology of UWB system is to design a compact, wideband and omni-directional antenna. During these ten years, planer monopole antennas are used as wide band antennas. However, two-dimensional 3GHz~5GHz UWB antennas are seldom investigated in the literatures. In this research, we propose a whole planer 3GHz~5GHz UWB antenna and employ both slit and parasitic methods to increase the bandwidth of the antenna with miniature characteristic.
    Two techniques are proposed to miniature compact design of the planar UWB monopole antennas and increase antenna bandwidth. One technique is to design the slit shape on the monopole radiator to miniature antenna. Antenna reactance can be changed by this slit shape structure instead of increasing the gap size between monopole radiator and ground plane which increases the antenna dimensions. By these two techniques, the antenna size can be reduced about 33%.
    To reduce manufacture cost and practical fabrication, we also propose a simplified antenna structure. Wideband characteristics of the simplified structure antenna are similar to that of semi-circular structure. Moreover, we also try to find the minimum size of the antenna. Wide band characteristics are defect when the dimension of the antenna is further reduced by decreasing ground length. However, slit structure method is employed to improve antenna wideband characteristic.
    Finally the antenna prototypes are fabricated and the antenna characteristics are measured. The antenna characteristics measured includes the S parameter and radiation patterns. The consistency between the simulated results and the measurement results confirm the practicability of these techniques.
    Appears in Collections:[Graduate Institute & Department of Electrical Engineering] Thesis

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