Very high resolution airborne synthetic aperture radar imaging at long range

Long range airborne SAR imaging with very high resolution is appealing in many applications for protecting the sensor aircraft or for avoiding its interference with existing air traffic. Extending range to imaged area yields several difficulties: First the increase in propagation loss is mitigated by increasing the transmitted power and using an high gain antenna (more directive). But, unlike satellite borne case, an highly directive antenna requires active steering for compensating aircraft attitude variations during signal acquisition. It may also require slowing or stopping antenna footprint sweeping on the ground in order to allow long integration time hence high azimuth resolution.