FCC amended its Part 15 rules to allow fixed point-to- point tran...

would be required to use highly directional antennas to minimize risk of potential interference to other services in band. Agency described order as paving way for new products and services in that spectrum, including management of network traffic on high- speed wireless Internet service or linking multiple building intra-office network. Part 15 transmitters typically are restricted to very low signal levels. Order said those transmitters operating in 24-24.25 GHz band were limited to field strength of 250 mV/m using directional antennas. Sierra Digital Communications had asked that FCC alter Part 15 rules to allow fixed point-to-point operations in band at field strengths of 2500 mV/m. Sierra had recommended that devices operating at that higher level be required to use antennas with certain gains. It had argued that directional antenna with minimum gain within certain limits would produce smaller area of potential interference than omnidirectional antenna operating at lower power levels. Difference is that under old rules, transmitter could use nondirectional antenna at lower power that would put out circular pattern, Washington attorney Mitchell Lazarus said. Under Part 15 change, potential area of interference is altered into long narrow cone, he said. “The area over which you are causing interference is no greater -- it’s just a different shape,” he said. “Using a directional antenna with either the specified minimum gain or maximum main lobe beam width will produce a narrow radiation pattern, thereby minimizing the area over which interference to other devices may occur,” FCC said. Commission said granting Sierra’s request was in public interest because “increasing the field strength limit will promote greater use of Part 15 unlicensed devices for purposes such as emergency restoration of communications in disaster situations, low-cost telecommunications delivery in rural areas and other beneficial applications.” American Radio Relay League had contended that amateur service in 24.05-24.25 GHz band used sensitive receivers that would be threatened by Part 15 devices as described in earlier notice of proposed rulemaking. Order said “these devices have been authorized to operate for years with no adverse effects to other users in the band, including amateur operations.”