Multi-channel SAR: Relaxing the minimum antenna area constraint

The imaging performance of conventional SAR systems is inherently limited, as swath width and geometric along-track resolution pose contradicting requirements to SAR system design. This restriction, often expressed as `minimum antenna area´ constraint, can be overcome by innovative multi-channel SAR concepts, such as systems with multiple receive apertures in azimuth. In general, reception by multiple receivers and appropriate digital processing of the signals adds a degree of freedom to SAR system design. More specific, it allows for decoupling the antenna length from the pulse repetition frequency (PRF). This can then either be exploited for optimized high-resolution wide-swath imaging, or enable decreased antenna dimensions while ensuring the system performance. This paper will present how multiple receiving channels permit to shorten the minimum required antenna length while keeping basic SAR performance parameters, such as azimuth ambiguity-to-signal ratio and geometric resolution constant. This includes a discussion of the benefits and the associated `cost´, such as an increased data rate and system complexity.