臺灣博碩士論文加值系統

在本論文中提出了射頻辨識標籤(Radio Frequency Identification, RFID)系統的標籤天線設計方法。製作上採用單面印刷電路板，使得天線的製造成本更具競爭力。

射頻辨識標籤天線設計這方面，我們預計達到的目標是使標籤天線能通用於全球RFID使用頻段，即可操作在860–960 MHz頻段内。射頻辨識標籤天線設計上將以雙迴圈(dual loop)的結構為設計主軸，並輔以外接Bow-tie天線的三角型金屬片使得RFID晶片及標籤天線之間的阻抗共軛匹配，實現目標頻寬，並有效提升讀取效能。天線在這種設計架構下，調整設計參數後可適用於不同廠商生產的RFID strap。

射頻辨識標籤即使處於電磁波微弱的環境下(如水包覆下)，藉由標籤天線中的雙迴圈結構讓標籤天線能以近場耦合能量的方式，有效捕獲來自讀卡機天線的能量，進而驅動晶片順利工作。利用能量耦合的模擬結果，加以分析並討論射頻辨識標籤讀取的可靠度，有助於RFID系統的建置。以上的設計方式使天線可操作在近場及遠場。

In this thesis, we propose the method to design tag antennas, which are suitable for radio frequency identification system. The fact that the tag antennas design comes with single layer printed circuit board can achieve cost down of the antennas.
For the tag antennas, the aim is to design the RFID tag antenna operating in 860–960 MHz which are suitable for both the near- and far-field operations worldwide. The method we use to design tag antenna is the dual loop form with Bow-tie antenna, and we focus on the impedance conjugate matching between the RFID strap and antenna to increase impedance bandwidth and improve reading performance. We can adjust parameter to be suitable for different RFID strap in the design framework.
The dual loop structure carries out power coupling efficiently in the near field and can allow the RFID strap to work even in the weak EM wave. According to the result of power coupling simulation, we analyze and discuss which factor will affect the reliability of the identification. Such reliability will help to build RFID system.

目錄
致謝.................................................................................................................................I
中文摘要......................................................................................................................III
英文摘要......................................................................................................................IV
目錄...............................................................................................................................V
圖表目錄......................................................................................................................VI

第一章 序論..................................................................................................................1
1-1 研究動機.........................................................................................................1
1-2 研究方法.........................................................................................................2
1-3 論文大綱.........................................................................................................2

第二章 射頻辨識系統..................................................................................................3
2-1 射頻辨識基本概念.........................................................................................3
2-2 射頻辨識工作原理.........................................................................................3
2-3 射頻辨識系統構成.........................................................................................5
2-4 影響射頻辨識讀取距離原因.........................................................................5
2-5 功率傳輸係數.................................................................................................7
2-6以圓極化天線設計讀卡機天線的考量..........................................................7

第三章 射頻辨識標籤天線結構設計........................................................................12
3-1 射頻標籤天線設計目標...............................................................................12
3-2 使用曲折型天線為設計的考量...................................................................15
3-3 融入Bow-tie結構的射頻辨識標籤天線.....................................................19
3-4 建構具有雙迴圈的Bow-tie天線結構設計實現寬頻.................................22
3-5 射頻辨識標籤天線設計與量測...................................................................34

第四章 射頻辨識標籤天線在近場場區的效能分析................................................39
4-1 天線近場基本原理.......................................................................................39
4-2具有迴圈饋入與否的射頻辨識標籤天線近場能量耦合分析比較………41
4-3射頻辨識標籤天線設計近場與量測............................................................48

第五章 結論................................................................................................................50
設計流程...................................................................................................................51
參考文獻......................................................................................................................52


圖表目錄
圖 ..................................................................................................................頁數
Fig. 2.1 射頻識別示意................................................................................................3
Fig. 2.2 標籤天線的運作方式(a)電磁反向散射(b)電感耦合...................................4
Fig. 2.3 UHF頻帶讀卡機天線設計...........................................................................9
Fig. 2.4 UHF頻帶圓極化天線特性(a)折返損失(b)Smith chart ............................10
Fig. 2.4 UHF頻帶圓極化天線特性(c)軸比(d)三度空間輻射場型........................11
Fig. 3.1 (a) SMA接頭(b) TI RFID strap...................................................................12
Fig. 3.2 天線的典型阻抗圖......................................................................................13
Fig. 3.3 天線饋入源方式..........................................................................................14
Fig. 3.4 饋入端具有迴圈的曲折型天線..................................................................15
Fig. 3.5 饋入端具有迴圈的曲折型天線之天線電流分佈圖..................................17
Fig. 3.6 饋入端具有迴圈的曲折型天線之天線折返損失......................................17
Fig. 3.7 饋入端具有迴圈的曲折型天線之阻抗圖..................................................18
Fig. 3.8 饋入端具有迴圈的曲折型天線之輻射場型..............................................18
Fig. 3.9 饋入端具有迴圈的Bow-tie天線................................................................19
Fig. 3.10 饋入端具有迴圈的Bow-tie天線之天線電流分佈圖................................20
Fig. 3.11 饋入端具有迴圈的Bow-tie天線之天線折返損失....................................20
Fig. 3.12 饋入端具有迴圈的Bow-tie天線之阻抗圖................................................21
Fig. 3.13 饋入端具有迴圈的Bow-tie天線之輻射場型............................................21
Fig. 3.14 饋入端具有雙迴圈且外接矩形結構的天線(TI strap) ..............................23
Fig. 3.15 饋入端具有雙迴圈且外接矩形結構的天線(TI strap)之電流分佈圖.......23
Fig. 3.16 饋入端具有雙迴圈且外接矩形結構的天線(TI strap)之折返損失...........24
Fig. 3.17 饋入端具有雙迴圈且外接矩形結構的天線(TI strap)之阻抗圖...............24
Fig. 3.18 饋入端具有雙迴圈的Bow-tie天線(TI strap) ............................................25
Fig. 3.19 饋入端具有雙迴圈的Bow-tie天線(TI n strap)之電流分佈圖..................26
Fig. 3.20 饋入端具有雙迴圈的Bow-tie天線(TI strap)之折返損失.........................26
Fig. 3.21 饋入端具有雙迴圈的Bow-tie天線(TI strap)之阻抗圖.............................27
Fig. 3.22 饋入端具有雙迴圈的Bow-tie天線(TI strap)之輻射場型.........................27
Fig. 3.23 饋入端具有雙迴圈的Bow-tie天線(TI strap)之3D輻射場型...................28
Fig. 3.24 饋入端具有雙迴圈的Bow-tie天線(Alien strap) .......................................29
Fig. 3.25 饋入端具有雙迴圈的Bow-tie天線(Alien strap) 之折返損失..................29
Fig. 3.26 饋入端具有雙迴圈的Bow-tie天線(Alien strap) 之阻抗圖......................30
Fig. 3.27 天線設計及調整參數..................................................................................31
Fig. 3.28 天線阻抗圖..................................................................................................31
Fig. 3.29 RFID天線的阻抗比較圖............................................................................32
Fig. 3.30 天線設計及調整參數..................................................................................33
Fig. 3.31 天線實做......................................................................................................35
Fig. 3.32 AWID讀卡機.............................................................................................36
Fig. 3.33 天線&SMA接頭..........................................................................................37
Fig. 3.34 天線場型量測與模擬..................................................................................38
Fig. 4.1 天線輻射場..................................................................................................39
Fig. 4.2 天線場區......................................................................................................40
Fig. 4.3 電感耦合......................................................................................................40
Fig. 4.4 圓極化讀卡機天線和長方柱的配置圖......................................................41
Fig. 4.5 電場場型(長方柱填充空氣).......................................................................42
Fig. 4.6 電場場型(長方柱填充水)...........................................................................42
Fig. 4.7 圓極化讀卡機天線和標籤的配置圖..........................................................43
Fig. 4.8 電場場型(長方柱填充空氣).......................................................................43
Fig. 4.9 電場場型(長方柱填充水)...........................................................................44
Fig. 4.10 近場模擬設置..............................................................................................45
Fig. 4.11 射頻辨識標籤天線......................................................................................45
Fig. 4.12 空氣中的S21 (55 mm) ...............................................................................46
Fig. 4.13 水中的S21 (55 mm) ...................................................................................47
Fig. 4.15 水中的S21 (45 mm) ...................................................................................47
Fig. 4.15 射頻辨識標籤置放水中量測......................................................................49
Fig. 4.16 射頻辨識標籤置放水中量測(以水面的法線為軸，標籤水平旋轉90度)49

Table 4.1 讀取距離量測(空氣中)...............................................................................35
Table 4.2 讀取距離量測(水中與空氣中比較)...........................................................48

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[7] K.Chang, S. Kwak, and Y. J. Yoon, “Small-size spiral dipole antenna for RFID transponder of UHF band,” APMC 2005. Asia-Pacific Conf. Proc., vol.4, 4-7 Dec. 2005.

[8] C.C. Chang and Y.C. Lo, “Broadband RFID tag antenna with capacitively coupled structure,” Electronics Letters, vol. 42, pp.1322-1323, Nov. 2005.


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