The paper describes a variety of ways to capture images through walls using microwave radiation. These techniques have already made their way into commercial products like L-3 CyTerra's RANGE-R and Camero-Tech's XAVER line of handheld through-wall radar units. The devices start at about $6,000.
TWI tech has been receiving government funding for more than a decade. DARPA debuted a handheld through-wall device called Radar Scope in 2006, to help US troops in Iraq. In 2012, according to USA Today, at least 50 law enforcement agencies in the US had such technology. CyTerra did not immediately respond to a request to provide more current figures.
Sparse blind deconvolution for imaging through layered media: