Abstract: To tackle the inability to measure the equivalent source reflection coefficient due to inseparable components, a new online measurement method for equivalent source reflection coefficient, based on the ripple method, is proposed. This method avoids the need for numerous matched/mismatched airlines or complex measuring devices. Instead, it employs a single matched airline and one mismatched power sensor to conduct a broad frequency band measurement of the equivalent source reflection coefficient, showcasing its simplicity and efficiency. The paper derives the expressions for the source reflection coefficient under amplitude stabilization and the equivalent source reflection coefficient when utilizing a power transfer standard. Furthermore, it elucidates the notion of "equivalence" in the source reflection coefficient from the perspective of the mismatch factor, analyses the effect of mismatch on power ratio measurement results, and proposes an online measurement method for equivalent source reflection coefficient through the mismatch factor. Experiments are conducted on a commercial power transfer standard within the 1-18GHz frequency range. The results meet expected indices and conform to the overall trend, thereby validating the feasibility of this method. The method serves as a reference for further research into wider bandwidth online measurement methods for the equivalent source reflection coefficient.