Theoretical considerations of bi- and multistatic SAR

The report discusses a new system concept for ground surveillance based on bi- and multistatic synthetic-aperture radar (SAR). The system has a number of tactical advantages compared to monostatic SAR, e.g. reduced vulnerability and improved update rate. The missile threat is reduced since the transmitting platform is operated at larger stand-off distance and the jamming threat is reduced since the receiving platforms are passive and do not emit radar signals. The update rate increases since receiver stand-off distance is reduced and the synthetic aperture can be completed in a shorter time. The disadvantages of bistatic SAR are technical difficulties associated with synchronising the transmitter and receiver, and to focus the SAR image without information of the transmit antenna position. The report describes bistatic SAR image formation and a model for image resolution. The model is verified by simulations and formulas for image resolution are derived. It is shown that bistatic SAR requires approximately twice the aperture angle to achieve the same resolution as monostatic SAR.