An integral equation which is convenient to calculate the transient response of dipole arrays is developed. The current distribution and radiated field of planar antenna arrays of straight-wire coupled antennas are calculated in the time domain especialy for short dipoles. The approximate method determining the transient response of large antenna arrays composed of short dipoles is discussed. The numerical results are interpreted in detail. The test about stability and convergence of numerical solution are carried out. The calculating time for transient response between time domain and frequency domain is compared.