具延長同軸線之射頻標籤讀取器匹配網路設計

Abstract

此研究主要貢獻是在於具有 RF 切換器及延伸長同軸電纜的 RFID 讀取 器設備之匹配網路開發，本論文進行電路模擬及實驗研究，首先，設計讀 取器線圈的磁場強度可以在規定的感應距離產生訊號耦合，但由於在讀取 器晶片差動輸出端口與印刷線圈之間插入了 RF 長電纜及平衡式轉非平衡 式的變壓器，非理想的變壓器及 RF 電纜改變了匹配條件; 因此，本作者重 新設計了匹配電路來實現當前的 RFID 規範，量測印刷線圈的磁場強度、 接收端的電壓和讀取器的功耗來證明此開發的匹配電路是有可用的，且可 以適用於具有延長電纜的情況。

The main contribution of this research is on the development of the matching circuit of a RFID reader equipped with a RF switch and long coaxial extension cables. Both the circuit simulation and experimental studies were carried out in this thesis. First of all, the coil was designed to provide the needed magnetic-field strength for signal coupling at the prescribed distance. Owing to the existence of a long RF cable, a balance-to-unbalance transformer was inserted between the differential output ports of the reader IC and the printed coil. The non-ideal performance of the transformer and the RF cables changes the matching condition; therefore, this author redesigns the matching circuit to fulfill the present RFID specification. The magnetic-field strength emitted by the printed coil, receiving voltage at the tag and power consumption of the reader were measured to prove that the matching circuit developed here is useful and can accommodate the scenario with a long extension cable.