Electric Scanning Doppler Steering Method for Pursuit Bistatic Small Satellites Strip-map SAR

Doppler steering is an important means to ensure the good operation of the spaceborne stripmap SAR. The traditional Doppler steering method of pursuit bistatic SAR is achieved by the separate yaw steering of master and slave satellites, which has a heavy dependence on factors such as antenna installation, beam width and baseline length. The beamwidth of high-band SAR is narrow, and the traditional Doppler steering would introduce a large gain loss; and for small satellites whose antenna points to the nadir, the yaw angle no longer changes the Doppler centroid. In order to solve the problems, this paper proposes a new method of Doppler steering for bistatic small satellite stripmap SAR. This method uses electric scanning to jointly adjust the beam pointing directions of the master and slave satellites, and ensures that the Doppler center is zero by solving the Doppler equation. Then the Doppler centroid variance can be suppressed without reducing the echo gain, and the limitation of the antenna installation orientation, frequency band, and baseline length is eliminated. Besides, computer simulations using the parameters of bistatic Ka-band small satellite SAR are conducted. The results are consistent with expectations, and the effectiveness of the proposed method is verified.