臺灣博碩士論文加值系統

無線電對講機採用的螺旋天線，因為天線本身頻寬較窄的特性，所以無法涵蓋無線電對講機的頻段132MHz~174MHz，天線必需調整其工作頻段。雖然軟體定義無線電系統SDR能應通信環境更變天線的工作模式，但是除非是智慧型天線或者是重構天線，否則在單一天線下，其天線輻射特性是很難隨軟體系統做更變的，所以在共振頻率之外的頻段因為阻抗匹配差的關係，連帶影響天線的輻射效率，造成訊雜比下降，影響的對講機的通話品質。
為了克服上述問題，本論文著重在頻率可重構天線於無線電對講機之研究，設計微帶天線結合PIN二極體的切換電路來達成頻率重構天線，因為微帶天線在尺寸有限下以及還要在微帶天線結構上加裝PIN二極體的切換電路，所以本論文分兩大部分來探討，一為運用幾何圖形的微帶線結構能等效LC電路之特性，對微帶天線進行阻抗匹配電路之設計，以調整天線阻抗來改善天線輻射效率，二以重構天線原理為基礎，以VHF折疊單極天線結構進行頻率可重構之天線設計，以PIN二極體來製作開關電路，來切換天線諧振長度，改變電流路徑的長短，進而調整天線工作頻段，達成頻率可重構之天線。
綜合以上天線設計之結果，本論文完成兩個部份，第一部份為提升VHF折疊單極天線的效率，經由量測結果能大約推算天線效率為15~17%，第二部份以VHF折疊單極天線結構為主，設計頻率重構天線，以二極體開關電路來切換共振頻率，並由量測結果證明，增益隨著共振頻率的切換而有所改變。

The two way radio usually used the helix antenna, has narrow band characteristic and it can't cover the The two way radio band 132MHz to 174MHz. The SDR system can tunable antenna working frequency, but In addition to the impedance of the resonant frequency, the other bands doesn't have impedance matching, and the efficiency will be down, and influence intercom the channel quality. So that the two way radio need a single tunable antenna and that can operate in various frequency bands.

This paper is study of used the microstrip antenna to design high efficiency meander line monopole antenna, it's using the microstrip line of characteristic can equivalent the LC circuit to matching Impedance, and upgrade the antenna efficiency, and last is using PIN diode switch to change the antenna resonant structure, and thus make the antennas has the frequency reconfigurable operated for three-band.

目錄

博碩士論文授權書......................................... i
論文封面............................................... ii
論文指導教授推薦書...................................... iii
論文口試委員審定書........................................iv
誌謝....................................................v
中文摘要................................................vi
英文摘要...............................................vii
目錄. ................................................viii
圖目錄..................................................x
表目錄.................................................xiv

第一章 緒論.............................................1
1.1研究動機...........................................1
1.2論文架構...........................................2
第二章 重構天線原理與應用..................................3
2.1概述...............................................3
2.2單極天線理論.........................................3
2.3重構天線原理與設計....................................5
2.4直流偏壓設置.........................................8
第三章 甚高頻折疊單極天線設計與分析...........................10
3.1甚高頻折疊單極天線模擬設計...............................10
3.1.1微帶線阻抗匹配結構的調整與影響..........................10
3.1.2天線位置的調整與影響..................................12
3.1.3甚高頻折疊單極天線設計總結..............................13
3.2甚高頻天線之量測結果與分析...............................30
第四章 頻率重構天線設計與分析..................................36
4.1頻率重構天線模擬設計......................................36
4.1.1甚高頻折疊單極天線結構分析與模擬...........................36
4.1.2天線搭配直流偏壓電路之模擬與分析...........................38
4.1.3頻率重構天線之模擬結果與分析...............................40
4.2頻率重構之甚高頻天線量測結果與分析............................57
第五章 結論與未來展望...........................................70
參考文獻........................................................73

參考文獻
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