A theoretical analysis of Ramsey fringes produced by the interaction of a molecular beam and a three‐zones electromagnetic resonator is reported. After averaging over the longitudinal velocity distribution of the particles, the relation between the fringe envelope width and the velocity distribution width is discussed. If the second‐order Doppler shift is introduced, the fringe envelope displacement is found to be of the same amount expected for the second‐order Doppler effect, but in the opposite direction. This analysis can be of some interest for the discussion of the performance of beam frequency standards in the near optical region.