Abstract A theoretical analysis of the waveform distortion of a rectangular r. f. pulse propagating through a guided uniform microwave transmission medium is presented. A nonlinear complex propagation constant as a function of frequency is assumed where the attenuation and phase constants are approximated by a quadratic. By applying Fourier transformation, an expression is derived for the exit waveform as a function of the propagation distance, attenuation, dispersion, and input pulse width. The derived expression has been formulated in terms of error functions of a complex variable. Results are discussed and illustrated in terms of the reduced relative amplitude of the pulse waveform due to dispersion and loss separately.