應用於RFID系統之讀碼天線多工切換模組研製

Development of Reader Antenna and Multiplex-Switching Module for Applying to RFID System

指導教授 : 黃榮堂、施勝雄  研究生 : 周致偉  機電整合研究所 94年


摘要


  本論文提出一組可應用於RFID無線射頻身分識別系統(Radio Frequency IDentification System)讀卡機端(Reader End)的天線模組與匹配控制電路。Reader與其配套軟體為資策會購於Alien公司的ALR-9780 High Performance,4-port UHF Reader與Tag來搭配。由於Reader的價格昂貴且只能佈置四個僅具有線性極化的天線,因此本論文將提出四個模組來改良該RFID系統。
  首先針對915 MHz射頻辨識系統讀碼天線進行分析與設計,期望能夠以更低成本、更小體積來取代Alien公司所生產之 Reader端收發天線。其中包含了圓形極化天線之設計,並比較各種不同基材材料對天線增益的影響。最後嘗試加入碎形之設計概念,並比較碎行程度對天線頻譜與增益之影響。接下來針對多工切換模組與功率控制模組進行分析與研製,目的在於設計一組數位邏輯控制電路,用來控制與切換不同的SPDT開關進而選擇多組天線的使用,並透過可調衰減器調控天線輻射功率。最後由單晶片網路伺服控制器(PIC_SERVER)完成整個系統之遠端連結,並開發一控制介面程式,安裝於近端電腦中。期望此設計概念能夠讓原RFID系統之性能更符合實際使用需求。
 

關鍵詞:射頻辨識,讀碼天線,圓形極化,天線增益,碎型天線, 多工切換模組,遠端控制
 

ABSTRACT

 This thesis presents an antenna module and a digital logic circuit for applying to the Reader of RFID (Radio Frequency IDentification) System. The ALR-9780 Reader, software and tag which produced by Alien Company are from III (Institute For Information Industry). Because the Reader is very expensive and it can only connect to four linear polarization antennas, we bring up four modules to improve the original system.
 Firstly, we investigate the design of 915 MHz RFID Reader Antenna and expect that the Alien’s Reader Antenna can be replaced with smaller volume and lower cost. It contains the design of circular polarization and finds the correlation between antenna gain and different substrate materials. Finally, we try to add a new concept of fractal, and find the correlation about antenna gain, antenna spectrum, and the space-filling properties of the fractal geometry. Secondly, we investigate a multiplex-switching module and power controller module in order to devise a digital logic circuit to control the SPDT switches and choose any antenna, and then tune the radiation power by the adjustable attenuator. Finally, the remote connection of the system is achieved by the use of the PIC_Server, and a PC-based control interface has also been developed. We expect these concepts can improve the performance of the original RFID system to match desired requirement actually.

Key Words: RFID, Reader Antenna, Circular Polarization, Antenna Gain, Fractal- Antenna, Multiplex-Switching Module, Remote Control.