ill tell you, the present state of the art for pinpointing moisture problem areas relies mostly on guesswork and a drywall saw. Based on hardware developed by Intelligent Automation, the new NIST technique involves sending a broad range of radio frequencies through typical drywall construction to look for a "moisture" signature in the signal that is reflected back. Laboratory experiments conducted with a simplified wall section made of gypsum board, fiberglass insulation, and oriented strand board (similar to plywood) demonstrated that the new method can locate moisture pockets to within one centimeter. The presence of water within the model wall produced a stronger reflection of radio waves at specific frequencies. The elapsed time between transmission of the waves and their arrival at a receiving antenna helps determine the loca- tion of the water. By processing the reflected signals with computer software, the researchers can create detailed three-dimensional maps that highlight wet areas. Research is continuing to see how well the apparatus performs with real walls that include studs, wires, pipes, and windows, which may complicate the readings. 6.9 MICROSCILLATOR Mobile phones and other radio-based devices could be created with the help of a new microscillator. The tiny, novel device for generating tunable microwave signals has been developed by researchers at NIST. The device measures just a few micrometers square and is hundreds of times smaller than typical microwave signal generators in use today in cell phones, wireless Inter- net devices, radar systems, and other applications. The technology works by exploiting the fact that individual electrons in an electric current behave like minuscule magnets, each one with a "spin" that is either up or down, just as an ordinary magnet has a north and a south pole. The device consists of two magnetic films separated by a nonmagnetic layer of copper. As an electric current passes through the first magnetic film, the electrons in the current align their spins to mat