Much of my own research has to do with uses and applications for phased antenna arrays.
One of the most exciting possibilities is that of using active and passive radio waves intercepted by a phased antenna array in order to map the surrounding environment. Different frequencies pass through different materials in different ways. By listening to these signals and triangulating their points of origin and interference patterns, it is actually quite simple to create a 3d visual representation of the surrounding environment just like a radar image. This technique can even see through walls.