This work deals with the effect of radio‐frequency waveform on the resolving power of an aperiodic rf mass spectrometer. The expressions for the energy‐gain function and resolution from one‐ to five‐stage analyzer configurations have been obtained with five different waveforms of the rf signal. The improvement of the resolving power obtained with square‐wave over sine wave excitation has been illustrated graphically for all the five configurations of the analyzer assembly. The effect of adding second harmonic to the sine wave, on the resolving power, has been investigated. The influence of inaccuracies in the grid‐positioning on the resolving power with sine and square‐wave operations has been discussed.