Detection of airborne targets by a space-based radar using multipath interference

It is shown that is possible to detect airborne targets from an orbiting radar using the low-frequency signal modulation caused by multipath interference. This method is effectively independent of target velocity and can therefore detect targets which are below the minimum detectable velocity limits of Doppler- or displaced phase center antenna (DPCA)-based radars, and also can provide a direct measurement of target height. It is suggested that multipath modulation could be used in conjunction with a velocity-sensing system such as Doppler or DPCA. The two systems used together would provide a greater probability of target detection, and better facilities for target classification, then either system on its own