On the concept and design of STAP-based SMTI modes with a small number of receive channels

Surface Moving Target Indicator modes are often implemented in radars that support a small number of receive channels (say N=2 to 4). The Space Time Adaptive Processing literature is very rich in studies for larger values of N, but not as much as been reported for small N systems. We describe some of the architectural and design parameter decisions associated with building an operational SMTI system, and then focus our attention on a single question: given a finite antenna size, what is the optimal way to split the antenna and process the data? In addition to architectural trade-offs and associated costs, the paper focuses on a single performance number - the Minimum Detectable Velocity. MDV curves are given for a number of configurations, including two channel, four-channel, and a “Ping Pong” mode which generates a third virtual channel from a two channel antenna. It is seen, that for the scenario under investigation (detection of small, slow movers with a relatively small radar with adequate PRF and well behaved clutter), the two channel system has the lowest MDV.