The use of S parameters in wireless power transfer system stability

In this paper a series of constants, corresponding to wireless power transfer system (WPTS), are defined, function of S parameters. These constants will be further used for stability factors computation in WPTS. To generate: the reflection coefficients, the standing wave ratio (SWR), the input and output impedances, the input and output active power transmission efficiency, the signal transmission efficiency, the power gains, the various stability coefficients, the centers and radius corresponding to stability circles from the source and from the generator, the S, T, Z and Y matrices and the Smith charts, we developed dedicated functions by using existing routines from the MATLAB Microwave toolbox. The results obtained by simulations were compared to those existing in literature and with experimental ones.