A modifi cation is proposed for a method of measuring various physical quantities using the area under the resonance curve as an information parameter of the measurement resonator. The modifi ed method consists of determining the amplitude-frequency characteristic (AFC) at a fi xed frequency with variation of the initial resonant frequency of the resonator within fi xed limits. In order to realize the modifi ed method, deviation from the oscillation frequency of the generator is not required. The realization of the modifi ed method is considered for measurements using waveguide resonators.