Full-time Resolution analysis and Path Determination for air borne Forward-Looking SAR with Opportunistic Illuminator

The bistatic SAR has forward-looking imaging capabilities if a opportunistic illuminator is selected to form the synthetic aperture. This would enable it to perform some inspection tasks that traditional SAR cannot perform. The system resolution of a bistatic SAR is related to its configuration. Due to the special configuration of the bistatic forward-looking SAR, the traditional system trajectory design method is no longer applicable. Therefore, a trajectory design method used for bistatic forward-looking SAR is proposed in this paper. First, the original trajectory of the receiver is determined according to the system which is always cannot be changed. Then, the slant range and the pitch angle of the transmitter are determined at each time. Next, the resolution of the transmitter under different squint angles at different times is calculated. Then, the available area of squint angle is obtained by drawing the results into a diagram. Finally, a position curve of the squint angle that is contained within the available area is found, and then the position of the transmitter and the resolution are calculated based on the position curve. The method can make the resolution of the forward-looking SAR system meet the requirements at all times under the condition that the changes to the original trajectory are at the minimum. The simulation results verify the validity of the proposed method.