Due to a lack of financial resources, we unfortunately have to suspend the import of any new radio frequency and mobile phone-related articles as of now (November 27, 2017). We apologize for this inconvenience and will keep you informed.

Because we received a large number of inquiries, we set up a bank account to accept donations. With their aid, we hope to resume, at least partly, the import of newly published articles to the RF archive of the EMF-Portal. Any contribution is greatly appreciated. Thank you for your kind support!

DONATION ACCOUNT: Uniklinik RWTH Aachen, IBAN: DE27 3905 0000 0013 0040 15, BIC: AACSDE33, Reference: GB-FM/380454/Arbm


Electromagnetic fields

In the extremely-low and low frequency ranges, the electric fields and the magnetic fields of a source must be considered separately. The higher the frequencies are, the closer these fields are linked or "coupled" to each other and are then considered as an electromagnetic field. However, the electromagnetic field has an electric and a magnetic field component. In the radiofrequency range, from a frequency of about 30,000 Hz (30 kHz) electromagnetic fields can “detach” from their source (e.g. an antenna) and freely pass through the room over long distances with the speed of light (about 300,000 kilometers per second). This property is used to transmit information, e.g. broadcast, television, mobile communication, and wireless data (see also Man-made radio frequency fields).
Electric field (E) and magnetic field (H) of a propagating, linearly polarized electromagnetic wave over time (t). E and H are in phase and at 90 degrees to each other and mutually generate one another.
The power flux density S of the electromagnetic field consists of energy fractions of the electric and magnetic field components and is measured in watts per square meter (W/m2). The field strength decreases with increasing distance from the field source.

In a frequency range between 100 kHz and 10 GHz the specific absorption rate (SAR) is commonly used to describe the energy of the electromagnetic field that is absorbed in biological tissue and there mainly converted into heat. The SAR is given in watts per kilogram of tissue (W/kg) and averaged over six minute exposure intervals in appropriate measurements or simulations. During this interval, a balance between the energy input and the heat dissipation in the tissue has been reached. By averaging over different body masses a distinction between the exposure of the whole body or parts of the body (e.g. the eye only) can be made.