noise and is very secure. However, there are issues when using omni-directional antennae such as attenuation loss or traveling through reinforced concrete. In order to overcome these types of obstacles, directional antennae must be placed if signal needs to travel more the 10 Kilometers. This media is also a turn off to many because of its high cost and the complexity of implementation. The antennae installed must be precise in its direction; the slightest deviation will result in failure of signal transmission. Generally, large corporations employ these media to interconnect LANs between buildings to bypass the local telephone company. Technology Spread Spectrum Narrowband Microwave Infrared Maximum Coverage 105 to 800 feet, or up to 50,000 square feet 40 to 130 feet, or up to 5,000 square feet 30 to 80 feet Line of Sight Required No No Yes Transmit Power Less than 1W (U.S.) or 100mW (Europe) 25mW Does not apply License Required No Yes No Inter-building Use Possible with unidirectional antenna No Possible Rated Speed (percent of 10 Mbps wire) 20 to 50 (most versions available) 33 50 to 100 ...
