A laptop with a wifi card or a wifi adapter allows wireless internet surfing. WiFi ('Wireless Fidelity') is a popular name for technology whereby connections in a computer network are wireless within a certain range. Such a wireless network is called a WLAN or Wireless Local Area Network. Other devices can also be connected to a WLAN, such as a PDA (‘personal digital assistant’) or a telephone (via VoIP: ‘Voice Over Internet Protocol’). The connection between all of the wireless devices is made via an ‘access point.’ Sometimes a wireless router (modem) serves as the access point. Devices that are connected to a WLAN can both transmit and receive
The transmitting powers of the devices and of the access point are very small and can be considered safe.
• A WiFi adapter has for instance a peak capacity of 100 or sometimes 200 mW.
• The average actual transmitting power of a WiFi adapter is always smaller than the peak capacity: the average actual transmitting power depends on the amount of data that is transmitted (the less data, the smaller the transmitting power).
• When a laptop does not transmit data, it does not send a signal. When an access point does not transmit data, a signal is still transmitted now and then (the beacon). A beacon signal has an average transmitting power of 0.5 mW.
These devices comply with the exposure standards with regard to the SAR value even for the largest possible data volume.
The electric field is used to get a good indication of the exposure because the SAR value cannot be measured just like that. Even using the maximum transmitting power and the largest possible data volume, the electric field at a distance of 20 cm is still less than 6 V/m. At a distance of one meter this has already dropped to 1.5 V/m. The graph shows how the electric field decreases with distance.
Tips to lower the exposure
In order to limit the exposure, the following simple measures can be taken:
• Only switch on your wireless network connection when it is needed. This concerns the wifi adapter in your laptop in particular. Otherwise, your laptop tries to continually connect to the network, and that leads to unnecessary exposure and decreases the life expectancy of the batteries.
• Place the access point away from places where you spend lots of time.
You can download all information of this section in its entirety as a PDF document (information sheet “Wireless devices”).