For every weapon ever conceived there is always a defensive device also conceived. Without getting into the efficiency factor or using an electronic counter device some 1 meter wide concave mirrors would reflect back, not to mention the ability to build lightweight radar absorbing outwear similar to that used on the F-117 stealth fighter. Authorities can brag all they want about high tech offensive hardware but usually its something very simple available to defeat it. I can just imagine a condensed microwave beam at a crowd, I have seen a demonstration of it, but take simple aluminum foil or mylar and you have a barrier or shield. A large concave or focusing mirror, opposite a convex mirror though that type of mirror can be used.
