Inductively Coupled Loop Antenna Design for Uhf Rfid on-Body Applications

Abstract—This paper presents a one-wavelength loop antenna fed by an inductively coupled loop for on-body applications. An equivalent circuit for the inductively coupled loop antenna is proposed to synthesize the antenna system with a microchip. The designed tag is printed on a PVC substrate and placed close to a four-layer stratified elliptical cylinder human model. The card-type tag measures 85.5 × 54 × 0.76mm3 and is suitable for use on a student ID card for a broad range of applications. The impedance bandwidth of the inductively coupled loop tag antenna is 60MHz (880–940MHz, 6.6%), which covers the operating UHF bands in U.S. and Taiwan. The measured reading distance ranges from 2.7 to 5.7 meters when placed at different positions on the chest of a human body in the open site. 1.