Single and multiple pass height finding interferometry from an airborne platform

There is increasing interest in the utilisation of height-finding interferometric synthetic aperture radar (HFISAR) for civil and military mapping, and large area change detection, applications. The technique has been demonstrated from spaceborne platforms using combinations of data collected from multiple imaging passes, and from airborne platforms which generically operate in a 'single pass' mode by deploying two physically distinct antennas. In the case of airborne operation there is a particular need to perform highly accurate motion compensation to the data in order to reduce height reconstruction errors to acceptable levels. The criticality of this is particularly evidenced in the case of multiple-pass airborne HFISAR. The present paper describes results arising from research which has been carried out at DERA (Malvern) UK on airborne HFISAR. Both single pass and multiple pass cases are considered. Theoretical performance is compared with the results of actual trials using the DERA long-range X-band Canberra system and the experimental DERA C-band single-pass system. The paper ends with a discussion of the expected performance of the new DERA long-range I-Band system, (ESR, Enhance Surveillance Radar), when operating in HFISAR mode.