We propose an antenna gain pattern estimation method for broad band antennas. We have already reported a method for estimating the far field gain using an amplitude center modified Friis transmission formula. This equation can estimate the far field gain using near field S21(ω) measurement for two difference antenna distance. In this paper, we propose a far field gain pattern estimation method using near field antenna pattern measurement of two difference antenna distance and amplitude center modified Friis transmission formula. We demonstrate that the E-plane gain pattern estimate for log periodic dipole array antenna by proposed method.