The invention discloses a method for improving the on-
orbit performance of an SAR
satellite based on electromechanical combined scanning, and the method comprises the steps: setting a moment when the
Doppler frequency of the echo of the center of an imaging scene is zero as an imaging center moment; setting ground aiming points of the
azimuth at different moments; calculating an instantaneous
echo time range according to the range of the slope distance between the
satellite and a scene; selecting a proper pulse repetition rate; determining the scanning range of an antenna according to the electric scanning capability of the
satellite antenna; calculating the number of
residence pulses according to the electric scanning range and a
beam scanning step value; calculating the electric scanning angles of the antenna at all the time points according to the constant-speed scanning law; calculating an attitude angle required by the instantaneous imaging according to the instantaneous
ephemeris data, the ground aiming points and the electric scanning angles of the antenna at instantaneous moments through employing a
vector method; judging whether a satellite
control system can meet the above attitude demands or not; and completing the
parameter design. Therefore, the method achieves the overall improvement of the image performances of an on-
orbit phased-array
system SAR satellite in the mode of electromechanical combined scanning.