In this paper we present the suitable formulation of S parameters using the electric circuit theory along with their practical use to improve the efficiency of the wireless power transfer systems (WPTS). We also present an algorithm used for computing S parameters. In order to compute the parameters S, for different structures of WPTS, we may use either the modified nodal equations, generated by circuit symbolic analysis program (CSAP), either the state equations, generated by symbolic state equation generation (SYSEG). Based on analog circuits theory in harmonic state in complex domain, the accuracy for defining parameters S is confirmed, comparing our results with the ones obtained using the advanced design system (ADS) software with specific routines.

Keywords: Wireless power transfer systems (WPTS), S parameters, Efficiency