Passive Synthetic Aperture Imaging

We consider passive synthetic aperture imaging where a single moving receiver antenna records signals that are generated by distant unknown noise sources and backscattered by one or several reflectors. The reflectors can be imaged by migrating the autocorrelation functions of the received signals. We compare this passive synthetic aperture imaging with the usual, active synthetic aperture imaging. In the usual synthetic aperture imaging the moving receiver antenna is also a transmitter, and imaging is done by application of a matched filter to the recorded signals. We show that image resolution is the same in both active and passive synthetic aperture imaging, provided that the illumination in the passive case is rich enough.