Its not as impressive as that article makes it look, I've seen more down to earth articles on it, and if this is what I think it is, its nothing more than shooting the rounds down. Literally, its an automated gun turret that locks onto the incoming rocket, then shoots the nosecone to detonate it before it can reach the target.
Think about it, if it was an actual force field of any kind, why would it need to lock onto an incoming shell with radar? You'll also notice that they say it won't work on things like ships, because you can't reliably fire counter measures through water.