A system and method for measuring and analyzing power flow parameters in RF-based excitation systems for semi-conductor plasma generators. A measuring probe (8) is connected to an RF transmission line for receiving and measuring voltage (10) and current signals (12) from the transmission line (4). A high-speed sampling process converts the measured RF voltage and current signals into digital signals. The digital signals are then processed so as to reveal fundamental and harmonic amplitude and phase information corresponding to the original RF signals. Multiple measuring probes may be inserted in the power transmission path to measure two-port parameters, and the networked probes may be interrogated to determine input impedance, output impedance, insertion loss, internal dissipation, power flow efficiency, scattering, and the effect of plasma non-linearity on the RF signal.