Somehow I doubt you are going to like to hear my response at all. The product below works by implanting small magnets into wooden panels which absorb radio waves. I wuld assume implanting the same kind of magnets in glass etc would do the same with radar, as both are obviously electromagnetic waves.

"Japanese magnetic wood aims to block mobiles
As reported recently, the Royal Canadian Mounted had to be granted special permission to jam the airwaves thereby preventing terrorists from using radio signals to remotely explode devices. That’s because radio jammers are illegal in certain countries including North America, Britain and Australia. However, a Japanese scientist Hideo Oka and his team from Iwate University in Morioka, Japan has developed a special magnetic wood that can effectively block common radio signals. According to a report in The New Scientist, Oka tested his wooden panels against GSM frequencies – 900 MHz and 1800 MHz as well as against 2.4 GHz. This means the panels will block signals used for both Bluetooth and Wi-Fi (802.11). Hence Mr Oka envisages this latest invention as proving useful for keeping wireless Internet signals inside a building so that competitors can’t hack into a corporate LAN. The panels contain magnetic ferrite sandwiched between layers of wood and the Iwate team believe such panels can readily be manufactured commercially. It could also solve the problem of mobile phones accidentally going off mid-act in the theatre."

http://www.mercola.com/2002/jul/20/cell_phone.htm

http://www.wapinsight.com/wap_insight_121.htm