GNSS-based SAR for urban area imaging: topology optimization and experimental confirmation

Synthetic aperture radar (SAR), which uses the global navigation satellite system (GNSS) satellites as transmitters (GNSS-based SAR), consists of the GNSS transmitter in orbit and reception equipment near the ground. GNSS-based SAR has widespread applications in the remote sensing domain, including urban area imaging, because of its low cost and ease of deployment. However, due to the limited power and bandwidth of a GNSS transmitter, the area of the acquired image is very small (with a typical value less than 1 km²). This study proposed a new multistatic SAR concept with GNSS transmitters and multiple receiving antennas to achieve the 360° coverage and the potential of larger urban area image acquisition. The system design and architecture theory, including the resolution analysis and topology optimization, were established in detail. A multi-angle imaging experiment based on BeiDou-2 navigation satellites was designed to validate the proposed concept and theory, and the experimental results demonstrated the effectiveness of the proposed concept and theory.