At one time, we had Mobile Tactical High Energy Laser for ships and fighters. This is a defensive laser that will destroy missiles out of the sky and weighs less enough to fit inside airplanes.
Now DARPA has created force fields, electric current armor that will possibly stop an RPG. It weighs 1 to 2 tons instead of 10 ton armor that protects against the same damage. The army spends $74 million on electromagnetic armor and gun research and development. The impacts have only left dents and scruffs. The British's Defence Science and Technology Laboratory are also working on their own.
It would last for only a fraction of a second, if timed correctly it could prevent rocket propelled grenades, which detonate on impact, from reaching their target. The supercapacitor could then be rapidly recharged ready for another attack.