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WLAN stands for “Wireless Local Area Network” and is used to set up local computer networks. In contrast to cable-connected LANs, laptops, smartphones and tablets are connected wirelessly with each other via radio waves. WiFi is often used as a synonym. Access to WiFi today is a matter of course in hotels, bars, restaurants, libraries and other public facilities. The use of WiFi in private households has also become indispensable. Users benefit from a wireless Internet connection, which offers greater bandwidth at a lower cost regardless of the cellular network.


So far, two unlicensed frequency blocks from the “Industrial, Scientific and Medical Band” (ISM) have been released for WiFi (2.4 GHz and 5 GHz). These are frequencies that can be used in industry, science, medicine and domestic areas.

WiFi uses pulsed high-frequency signals. This means that a signal is not continuous, but instead is turned on and off in a certain rhythm. This is colloquially referred to as WiFi radiation. Small data packets are usually transmitted via a Wireless Access Point (WAP) or by a router in the private sector to all stations in the reception range. The information leaflet “Speech and Data Transmission via Radio Waves: Bluetooth and WiFi” of the German Federal Office for Radiation Protection ( contains the following information:

“WiFi and Bluetooth use the 2.4 GHz ISM band. In addition, the frequency ranges from 5.150 to 5.350 and 5.470 to 5.725 GHz have been released. The maximum permitted radiated power depends on the frequency range:

– 100 mW in the 2.4 GHz ISM band,
– 200 mW 5.15 to 5.35 GHz (use is only permitted within enclosed spaces such as buildings and aircraft)
– 1000 mW 5.470 to 5.725 GHz. Frequencies above 5.25 GHz may be used only with automatic power control; otherwise a 50% lower maximum level applies.

The maximum radiated power levels are based on an imaginary standard antenna that radiates in all directions. Directed radiating antennas may be used if approved radiation powers are respected.”

The ranges of the WiFi devices reach from 25 m (in buildings) up to 150 m (outdoors). If special directional antennas are used, the range can be extended to several kilometers. Entire cities can be connected by WiFi today.

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