Of the wireless LAN frequency bands that are available for use in Japan, the 4.9 GHz band is particularly promising as a reliable means of high-speed data transmission because interference and conflict are expected to be low - the expectations are that the 4.9 GHz band will not be shared with other systems and that it will require registration and so have a limited number of users. JRC has developed a module for use with 4.9 GHz wireless LAN devices. This module uses a lowdistortion power amp and a specialized band filter to effectively reduce unnecessary radiation such as spurious radiation and out-of-band radiation. This has enabled the use of a high-gain antenna for long-distance transmissions. Additionally, the module's small size and low power consumption have been achived.