Effective parameters for ferrite-core RFID tag antennas

Abstract

In this paper we obtain the effective geometrical parameters of a ferrite-core based antenna to model its equivalent electrical circuit for computing the self-inductance, power losses, including the hysteresis effects. The ferrite coil is the receiver antenna of a low frequency RFID tag (134.2 kHz). Non-linear effects are modeled by adjusting the hysteresis angle and effective radius of the ferrite core-based coil. In addition, we modeled the coupled equivalent circuit of the RFID system and computed the mutual inductance at different Z-axis values. Numerical analysis using FEM in 2D is used. These models have been validated with experimental measurements of S11 scattering parameter and induced current, respectively.