T-MATCHED DIPOLE TAG ANTENNA FOR UHF RFID APPLICATIONS

Recently, Radio Frequency IDentification (RFID) systems have been rapidly developing in the Ultra High Frequency (UHF) band due to the different advantages offered in different fields.The main goal of this paper is to present matched dipole tag antenna, fitting worldwide passive UHF RFID applications. The antenna is printed on an FR4 substrate with ε_r=4.7; it has a size of 139×6.75×1.635 mm^3. T-matched chart was also designed to match the antenna tag IC including a charge capacitor which compensates the large conductive reactance of the antenna impedance. Furthermore, the power from the antenna can be maximally delivered to a tag IC unless the antenna impedance is conjugately matched with that of tag IC. Simulation results demonstrate that the antenna has a suitable operating band from 759–947 MHz; it has nearly omnidirectional radiation patterns with proper gain.