Researchers at Ohio State's ElectroScience Laboratory say they've created a radar system that that is virtually undetectable when used, and able to penetrate solid walls to boot -- no doubt a significant boon to military, law enforcement, and disaster rescue operations. The radar works by scattering a very low-intensity signal across a wide range of frequencies, effectively disguising itself as random noise, but apparently not actually interfering with devices because its bandwidth is much broader than the signals it's hiding in. Although it's hardly the first to pull off wall penetration, the entire radar system can be built from components totaling less than a hundred bucks. But hold up before you run out to Radio Shack, because it shouldn't come as much surprise that they aren't providing detailed DIY plans. In fact, it sounds like those industrious Ohioans already got this system patented and are looking to license the IP -- so cheap gear or not, when it comes to the tech you gotta pay up or shut up.