DOLEV technology,When Theory Meets Practice
EMF Radiation shielding
Shielding of electromagnetic fields Concept of electromagnetic wave is understood as a disturbance of electromagnetic field, caused by changes of electric loads’ arrangement, dispersing in space. Electromagnetic wave is transverse wave, which one can characterize by vector of electric field and magnetic field’s induction vector. These vectors are mutually perpendicular to oneself and lie on the surface
a) Shielding of electric fields,
b) Shielding of magnetic fields,
c) Shielding of electromagnetic fields.
For shielding electric fields occurrence of electric loads accumulation in state of equilibrium on the conductor’s surface is used, independently from how the loads came into being. For particular area’s protection from electric field, it is shielded by screen in form of a coat or net creating so-called. Faraday’s cage.
Shielding of magnetic fields is used when we deal with slow changing or static magnetic fields. For shielding such fields we use ferromagnetic screens of large magnetic permeability
Shielding alternating electromagnetic fields of small and middle frequency requires screens, joining good magnetic properties and good conductivity (such set of properties most can be obtained for multi-layers screens, made of different materials). Shielding electromagnetic fields with higher
Frequencies (above 700 kHz) will require ferromagnetic screens with large conductivity. In this range of frequency epidermical effect appears, in result of which electromagnetic wave is extinguished in depths of half wave’s length [7].
From the point of view of its destination one can distinguish two kinds of electromagnetic field shields [8]: anti-disturbance orhygienic. Levels of admissible electromagnetic disturbances are specified by different standards, in this also Polish
We can indicate general rules of screen’s material selection:
Þfor shielding magnetic fields with low frequencies ferromagnetic materials with large magnetic permeability are suitable [7],
Þ For shielding electric fields the most useful are materials with large electric conductivity,
Þ For electromagnetic fields with higher frequencies the influence of higher material’s conductivity on attenuation of the screen increases,
Dolev – The largest EMF shielding producers Company in Israel provide innovative solutions for more then 20 years ,
experience of the control and use of electromagnetic fields. the company dealing in wide range of frequencies.
