The characterization of linear electrical components for frequencies up to a few MHz can be performed through impedance spectroscopy techniques that include the determination of the impedance frequency response and the algorithms that identify the equivalent circuit components. However, at higher frequencies some extra challenges are present since it is not practical to measure the impedance frequency response and s-parameters need to be used. Although the conversion between s-parameters and equivalent impedance matrix is well known, the application of the circuit identification algorithms is not straightforward.
This paper presents a procedure to perform circuit identification, through impedance spectroscopy, for components that operate on UHF. The data is acquired through the s-parameters and the equivalent circuit is obtained by using evolutionary algorithms, namely genetic algorithms and gene expression programming. The procedure is validated through the experimental characterization of an RFID device.