Abstract: In this paper, aiming at the non-ideal characteristics of the radio frequency switch in the time-modulated array antenna, the harmonic characteristics of various modulation waveforms are studied. First, the Fourier coefficients of the asymmetric trapezoidal/raised cosine waveforms are deduced, and the influence on amplitude, phase and energy proportion of two waveforms are analyzed. On this basis, an experimental modulation waveform are obtained through experiments, and trigonometric polynomials are used to fit the rising and falling edges of the real modulation waveform. Finally, the difference between various waveforms and harmonics is discussed. The results show that compared with existing modulation waveforms, the modulations of the asymmetric trapezoidal waveform, asymmetric raised cosine waveform and the fitted waveform proposed in this paper are closer to real waveform.