Grounded radiant barrier (matte white vinyl with aluminum on reverse side) in 48" rolls will block wifi and temperature for $0.25 per sq ft.
2023, https://www.policemag.com/technology/article/15541542/first-...
> “Once you place it against the wall, it takes one scan to show you where everything is, then over time anything that moves will pop up.. It can detect someone moving through the room or someone sitting on the couch and breathing. The small movements of breathing are enough for the radar to discriminate between the couch and the person.”
2015, https://www.usatoday.com/story/news/2015/01/19/police-radar-...'
> At least 50 U.S. law enforcement agencies have secretly equipped their officers with radar devices that allow them to effectively peer through the walls of houses to see whether anyone is inside.. The radars were first designed for use in Iraq and Afghanistan. They represent the latest example of battlefield technology finding its way home to civilian policing and bringing complex legal questions with it.
The police in Netherlands also operates these from inside vans. Most likely other countries too. They do this most busy weekends in the Dam Square for example. You walk by you get a full body scan to see if you have weapons on you I guess. I hope they like my butt.
Would be a shame if they'd arrest someone for carrying a toy gun or a gun-shaped ball of aluminium foil.