The globalized simulation of the response of the mono-pulse antenna in the near field region of the scatterer is done by using the method of moment(MoM)and the multi-level fast multipole algorithm(MLFMA) to evaluate quantitatively the performance of the angle measurement in near range for mono-pulse antenna.In this model the amplitude and the phase distribution of the scattering field in near region

and the radiation and the receiving response of the mono-pulse antenna are calculated accurately through the full wave analysis.First

the radiated field from the antennas with the summation beam

as the incidence to illuminate the target

is calculated.Then

the scattered field in the near region produced by the target

as the incidence to the received antenna

is simulated numerically.Finally

the electric signals received by the antennas with the difference beams are calculated and the measured angle is obtained by using the phase-comparison or the amplitude-comparison of the signals received from difference beams.The errors of the measured angles and its sources are discussed.The numerical results in the example with a missile-like target show that the angle measurement based on the summation and the difference beams of the mono-pulse antenna in the near field result in remarkable errors

and the application of the signals with the relative lower frequency dead to the less errors of the angle measurement.The corresponding physics behind above phenomena is given and the recommendation of the lower frequency signal for near range measurement is presented.