Design concepts for distributed synthetic aperture radar enabling innovative missions and imaging techniques by microsatellites

New design concepts for sensors, systems and satellites are crucial to enable innovative and high-performance working modes. In this contest, the concept of distributed aperture is becoming of a strong interest for the future Synthetic Aperture Radar (SAR) systems. It is based on the idea that the signal emitted by the transmitter and scattered from the area of interest is not collected by a single receiver but by many, conveniently distributed, formation flying, receivers, and, thanks to passive operations, can achieve very high performance through a series of very compact, low weight, agile, satellite platforms. The advantages of such system are innumerable and the potentialities of reliability, flexibility and modularity make it a very interesting approach for the future missions. However, a number of technological and operational issues shall be solved. The formation acquisition after launch, control and maintenance are big challenge. Also, a small satellite-based distributed SAR system may pose challenging requirements in terms of electrical power, communication link, and payload synchronization. In this ambit, the recent technology upgrades have led to the development of small platforms with increasing capabilities, thus opening the way for using distributed space systems also for cost-effective operational, public and commercial services. Finally, signal processing related issues shall also be solved to enable high-performance applications, not reachable by existing systems. The paper is focused on the distributed SAR concepts, showing: (a) main design drivers, (b) main issues to be solved and related approaches and (c) main potentialities.