Design and analysis of 13.56MHz RFID antenna based on modified wheeler equation: A practical approach

An RFID tag antenna in coil form with typical credit card dimension (78mm × 41mm) which is suitable for ISO 14443 standards was built virtually in Electromagnetic simulator and its result was later validated with identical physical antennas. A simplified equation of inductance in microstrip form by H. A. Wheeler is then compared to result found using data from the simulation and modified to fit it. Consecutively, specific matching impedance for each coil is calculated which the matching impedance represents an RFID tag plus its compensation impedance. The coil and the matching impedance will then be modelled in an RF system simulator and its impedance plot will be explained.