WASHINGTON, D.C.: Federal regulators have approved a plan to give away a section of the radio spectrum for free along with unlicensed high-speed wireless communications at distances of up to three miles. The plan was heavily backed by WINForum, a coalition of wireless providers including Motorola, Hewlett-Packard and Apple, all of which are creating equipment to work on the new frequencies. But don't go throwing away those ethernet connections just yet. Presented as a way to offer cheaper Internet access to schools and businesses, the plan still has some drawbacks. For many, price will remain an obstacle, since in order to take advantage of the spectrum, people will need costly new equipment. There is also the scope and power of the radio waves to consider. For many small towns and rural schools, the three-mile transmission limit may be too small to make this method feasible. In cities, the signals are expected largely to be blocked by heavy brick walls.