Electric armor is one method:
For several years, up until 2003, the U.S. Navy mentioned electromagnetic armor, or DAPS (Dynamic Armor Protection System) being developed for the planned CVN-21 class of carriers. The basic technology behind DAPS was not complex. Areas above the waterline would have two layers of thin armor, separated by a small air space. The two layers of armor would be electrified, and when the armor was hit by a shaped charge (favored for cruise missile warheads) the jet of superhot plasma, formed by the shaped charge warhead going off, would be broken up by the electromagnetic field formed when the two layers of armor were forced together. The big problem with DAPS was the huge amount of electricity required when the system was turned on. However, in the next decade or so, warship power plants are expected catch up with the needs of DAPS systems.
Pretty cool. Of course, this only works for slow missiles using shaped charge warheads. Our armored vehicles would still be vulnerable.
Traditional kinetic penetrators fired at high velocities using mass to punch through armor would defeat this type of armor. Old-fashioned guns will defeat this. And the shells wouldn't even need to be fired from big guns if the targets were thinly sheathed for lightness. Plus, we are working on high-speed line-of-sight missiles that would rely on sheer kinetic energy to punch through armor. Mines would also still be effective, even if only to knock off tracks or blow wheels.
Ships would have more protection since coming within gun range will be difficult. But even here we are looking at longer range guns. Plus, guided ballistic missiles would pack a huge kinetic energy potential. Still, this defensive advance does seem to be a major plus for surface warships.
Even infantry won't be helpless against armored vehicles without traditional bazooka-type weapons. Radios and designators could call in long-range fire more effective than having your own personal anti-tank weapon.
Still, the electric armor would be effective against insurgents who won't have distant firepower and rely on those RPGs and EFP ambushes.
Of course, perhaps the traditional anti-tank rifle in the 25mm range would make a return to the battlefield.
So bulky passive armor isn't obsolete as far as I can see. Although fitted to the vulnerable top, sides, bottom, and rear of an Abrams, electric armor would really add protection from top-attack munitions and other HEAT warheads in the hands of enemy infantry.
I guess I'm still far from convinced that the main battle tank is on the way out.
