SARK-110 100kHz to 230MHz Antenna Analyzer for HF RFID

Introduction The SARK 110 antenna analyzer is a convenient tool for the measurement of antennas for HF RFID applications because features such as the graphical representations of the impedance the determination of the sign of the reactance and good accuracy characteristics Besides starting from firmware version v0 8 3 2 the analyzer implements a very convenient feature for this kind of applications which is the automatic calculation of the equivalent circuit model of small loop antennas or coils The purpose of this application note is describing the step by step procedure of the use of the SARK 110 for this application using a practical example This procedure will consist in the measurement of a 13 56 MHz RFID reader printed coil antenna the determination of the equivalent circuit model and the matching to the reader output impedance 50 ohm in this case The RFID antenna used in this application note is realized as a printed coil on a FR 4 board substrate The series equivalent circuit is used to simulate the antenna in a RF simulation software and calculate the matching network I have used the freely available RFSim99 simulator but any other suitable simulation software can be used After designing the matching network the simulation results are verified with the measurement results Specifications General Frequency range 100 kHz to 230 MHz Frequency resolution 1 Hz Frequency stability 30 ppm Sine wave output RF Connector MCX socket Output power approx 10 dBm