http://www.spectrum.ieee.org/nov05/2146
Willie D. Jones
"Researchers have been working on radar that can 'see' through walls, so police can know where hostages are congregated or soldiers can tell where the enemy is lying in wait. Two devices that meet demanding criteria are on the market, and one has been adapted for use by the U.S. military in Iraq.
Some conventional radar can penetrate walls, but it cannot distinguish objects just ahead, it emits far too much power to be safe for operators, and it requires equipment about the size of a lab bench. Advances in digital signal processors and microwave integrated circuits have made it possible to fit a complete microwave system in a box the size of two encyclopedia volumes. Now, through-the-wall radar devices that are lightweight, portable, and able to focus up to 20 or 30 meters ahead are available to municipalities and law enforcement agencies. "
