Years ago tehre were t-shirts which would light up in presence of 2.4GHz frequencies. Like http://www.xoxide.com/wifi-tshirt.html http://www.xoxide.com/wifi-ts

Years ago tehre were t-shirts which would light up in presence of 2.4GHz frequencies. Like http://www.xoxide.com/wifi-tshirt.html http://www.xoxide.com/wifi-tshirt.html