WAGO-I/O-SYSTEM 758
Appendix
71
758-915
Bluetooth
®
ETHERNET Gateway
Manual
Version 1.1.0, applicable from FW/HW Version 01/01
8.7
Health Considerations
The device emits microwave radiation. It is explained in the safety instructions
that the device is not meant to be directly operated while in contact with the
human body. As with any other type of radio waves, there is a certain degree of
interaction between microwave radiation and human tissue. The intensity of this
radiation in the frequency range used by the device is, however, the decisive
factor in determining whether these effects can be measured or whether they may
even be harmful.
Despite their related frequency ranges, communication devices are in no way
comparable to microwave ovens, which operate at a considerably higher power
level (600 W and higher) and concentrate their energy into a tightly enclosed
compartment in order to achieve the best effect.
Radio communications devices, which are allowed to communicate license-free
throughout the world in the ISM band at around 2.45 GHz are, on the other hand,
subject to legal provisions restricting their transmitting power to 20 dBm EIRP
(“equivalent isotropic radiated power”), which corresponds to an output of
100 mW = 0.1 W.
Commercially available cell phones, which are carried close to the body or held
up to the ear, operate at frequencies up to 1.95 GHz and may only have a
transmitting power of up to 2 W EIRP. In-car phones and other similar devices
which are not carried on the body may even have a transmitting power of up to
8 W. These values exceed the maximum, permissible transmitting power for
Bluetooth
®
technology in the ISM band by a factor of 20 or 80.
The distance to the antenna must also be taken into account here. At a distance of
merely one meter the field strength already drops by 40 dB, which corresponds to
a factor of 100.
Therefore, based on current knowledge the following can be said:
When used properly, the risk of hazards or injury to humans by radio waves used
in
Bluetooth
®
technology can be ruled out.
