Integrated design of synthetic aperture radars for unmanned aircraft

The use of synthetic aperture radar (SAR) on unmanned aircraft (UAVs) is often contemplated for aerial observation of regions where unmanned, long duration (tens of hours) observations are advantageous. Some current applications are severe weather, military surveillance and environmental observations. However, in most cases the initial SAR and aircraft designs are done independently and one is either trying to design a SAR to fit a particular UAV or a UAV to fit a particular SAR. For example, Schwartz et al. (1990) designed and built a SAR to fit the Amber UAV (Cassidy, 1991). This process is likely to lead to a restricted range of choices to accomplish a given objective and fails to provide the system designer with a complete range of possible choices and trade offs. The authors develop a first order, integrated approach to design in which the SAR and aircraft designs are coupled. This approach allows a broader exploration of the options available in SARs for UAVs. There are a number of ways in which the SAR and aircraft interact. For example, radar echo power is influenced by antenna size, but aircraft size constrains the antenna size-as does azimuth resolution. The aircraft velocity V impacts virtually all aircraft relationships as well as SAR azimuth resolution. For applications that push the limits of small UAV SARs it is important to note that the aircraft power plant will need to power both the aircraft and the SAR