The liquid triple-stub tuner was adopted to obtain the impedance matching for antenna load of ion cyclotron resonance heating. Under the condition of impedance matching, the frequency modulation technique was used to reduce the reflected power caused by the change of antenna loading. The relationship between reflection coefficient and antenna loading before and after frequency modulation was numerically simulated to everify the effect of frequency modulation on ICRH system impedance matching device. The numerical simulation results show that th...