I'd imagine the Army relies, to a fair extent, on the tried and trusted technique of using people as a detection system. Watchtowers and patrols and the suchlike.

As someone said, that method would be much cheaper for the airport and would help solve the unemployment problem in the U.S.

However, I guess it doesn't sound so nice in the "tough stance against terrorism" as a "state of the art" defense system.

Just have to market it as a "military-grade intrusion detection system" or something.

I have one, it is called a dog.

They're pretty good for perimeter patrol, the Uruguayan military uses them, it's not a bad suggestion at all.

The state-side bases I have been to have been protected by physical layers only. The outer layer which goes around the whole base would have the usual barbed wire top and those big poles to prevent people just ramming their car right through the fence. This layer usually has a dirt road on the inside where the security forces routinely cruise the perimeter looking for evidence of tampering etc. If there are electronic detection mechanisms in use, it isn't apparent. The gates through this layer is guarded by men/women with automatic weapons, trucks, road spikes and a secondary wall they can raise up 100m in base in case someone just tries driving past the guard. Then any sensitive buildings within the base are usually guarded by a second layer of barbed wire fences. The perimeter of this layer is usually well within sight of more armed guards with trucks. Then getting into buildings within this compound involves more cameras, badges, codes, but probably most importantly: the regular people who work there take security pretty seriously and have no problem confronting people that look or act suspicious or don't have a badge, etc. It may not be as technologically advanced as this system described in the article but its probably far cheaper and far more effective.