A Passive Circulator for RFID Application with High Isolation using a Directional Coupler

Author

Kim, Wan-Kyu ; Lee, Moon-Que ; Kim, Jin-Hyun ; Lim, Hyung-sun ; Yu, Jong-Won ; Jang, Byung-Jun ; Park, Jun-Seok

Author_Institution

Sch. of ECE, Seoul Univ.

fYear

2006

fDate

10-15 Sept. 2006

Firstpage

196

Lastpage

199

Abstract

In this paper, a newly invented circulator for T/R switch of UHF radio-frequency identification (RFID) application is proposed to overcome TX-to-RX leakage problem. A microstrip coupled-line directional coupler is used for this passive circulator and the isolation characteristic is drastically improved not by complex method such as compensating phase velocity, but by considering both directional coupler itself and imperfect input impedance of the employed antenna. The measurement result of the proposed circulator using modified microstrip coupled-line directional coupler with employed antenna shows excellent TX-to-RX leakage suppression in the 860 MHz - 960 MHz, more than 45 dB enhancement at the center frequency compared to the conventional coupler. Experimental verification using RFID system is also performed to prove the validity of the proposed circulator

Keywords

circulators; directional couplers; interference suppression; radiofrequency identification; 860 to 960 MHz; RFID; T/R switch; TX-to-RX leakage suppression; UHF radio-frequency identification; imperfect input impedance; isolation characteristic; modified microstrip coupled-line directional; passive circulator; Antenna measurements; Directional couplers; Directive antennas; Frequency measurement; Impedance; Microstrip antennas; Passive RFID tags; Radio frequency; Radiofrequency identification; Switches; Coupled line directional coupler; RFIDHigh Isolation; TX-to-RX leakage;

fLanguage

English

Publisher

ieee

Conference_Titel

Microwave Conference, 2006. 36th European

Conference_Location

Manchester

Print_ISBN

2-9600551-6-0

Type

conf

DOI

10.1109/EUMC.2006.281252

Filename

4057781