New technologies: Wireless computer networking
[Archive CMO Feature - Last updated: 31/08/05]
Wireless local area networks (WLANs) are becoming widespread and replacing wired computer networks in offices, schools and homes. People with suitably equipped computers can also use the technology to connect to Internet services at remote locations where there are wireless "hotspots".
These computers are called 'clients' and either have radio antennas mounted outside their body-shell, or are integrated internally in order to transmit and receive radio signals carrying the data. Often the antennas are on removable cards that can be slotted into the side of the computer. Clients communicate with networks through radio 'access points', usually with their antennas mounted on nearby walls or ceilings. These may be, for example, in airports, rail stations and coffee shops.
Exposures depend on how the transmitting antennas are located with respect to the body, and the duration and power level of any transmissions.
Typical maximum emitted power levels during transmissions from equipment often used in the home are up to a few tens of mW and therefore somewhat lower than the powers from a mobile phone. However, the separation of the transmitting antenna from the body is typically 10s of cm rather than the 1-2 cm with a phone, and this considerably reduces exposures. Most equipment uses frequencies just below 2.5 GHz and slightly above those used by mobile phones.
