An antenna scan simulator has been developed for the real time radar electromagnetic environment simulation. The simulator is composed of man machine interface, digital compensation control, attenuation of high dynamic range, temperature compensate, wideband pulse modulator and power amplifier. The variations of gain of different antenna scans are pre-computed and stored as a data table in the simulator. After the parameters of antenna scan are set through the man machine interface, the values of amplitude attenuation can be acquired by table lookup and is transferred to digital compensation control. Then the attenuation module varies the radio signal with time, which is realized by integrated digital attenuator and PIN diode. Temperature compensate maintains the temperature error of power in a certain design range. Wideband pulse modulator can make continuous wave or wide pulse modulated signal into narrow pulse modulated signal. Finally, a power amplifier is used to compensate the insertion loss. The simulator can be connected directly to the commercial microwave signal generator to offer a comparative real antenna scan signal.