許耀文 博士 (國家太空中心)
Compared to single-receiver monostatic SAR, multi-receiver SAR can provide different aspects of the SAR image with a single acquisition. This talk would summarize some recent developments of Multi-Receiver SAR, particularly in MTI and bistatic SAR.
MTI, moving target identification, is a valuable application of SAR. Traditionally, a moving target will cause blurring or ghost in a single receiver SAR image. Segmental image formation may help to identify the moving targets, but is more suitable for targets with lower speed and larger RCS, such as ships. Multi-receiver SAR image may compare the phase difference between two receivers and therefore distinguish static and moving targets, and recent research can further evaluate the velocity and direction of the objects.
Bistatic SAR is a SAR image where the transmitter and receiver are no longer colocation. These images can reveal more RCS than monostatic SAR. Traditionally, this is accomplished by formation flight of platforms, and then the combination of spaceborne and airborne SAR is verified. With a much shorter distance to the receiver, the airborne image can locally provide much higher SNR, in complement to the spaceborne image. Recently, the passive radars, radars without transmitters, is popular to assist the spaceborne image because of the much lower cost and power consumption, making them easy for deployment in static location or on drones. The complementary data can provide SAR images with different baselines with a single acquisition. Yet, the perfect time synchronization between the transmitter and receivers is the major difficulty.
