 a similarly sized array featuring conventional square boundaries. A Peano-Gosper fractile array produces no grating lobes over a much wider frequency band than conventional periodic planar square arrays. "Grating lobes are sidelobes with the same intensity as the mainbeam," ANTENNA TECHNOLOGIES explains Werner. "They are undesirable because they take energy away from the main beam and focus it in unintended directions, causing a reduction in the gain of an antenna array." Penn State is in the process of patenting the team's approach to Peano- Gosper and related fractile arrays. The team has also been awarded a grant through the Applied Research Laboratory to build and test a prototype antenna. 6.10.5 Towers in the Sky Although antenna design and construction is important, SO is placement. In radio, generally speaking, the higher an antenna is placed, the better it will function. That's why satellites work SO well. But satellites are very expensive to build and launch. That's why a couple of companies are aiming their sites somewhat lower. "A big problem the U.S. has is that 80 percent of the population lives in just 10 percent of the land," says Knoblach, citing 2000 U.S. Census figures. "If you build only towers, you could never build the number needed to cover that sparsest 20 percent of the country because of economics." Space Data's SkySites project plans to launch radio transceivers connected to latex, expendable weather balloons from 70 sites in 48 states by the end of 2004. The balloons, which are 6 to 8 feet in diameter at launch but grow to about 25 to 30 feet in the air, are designed to float to 20 miles above the earth's surface, and will provide communications services for approximately 12 to 24 hours. At that point, they'll be replenished with a new "constellation" of balloons. The company claims it can launch its weather balloons twice a day, year- round for about $15 million to $20 million a year, significantly less than what most carriers would spend on towers to fill the same coverage area. Spac