Cell phone jammer needs no maintenance

For high-frequency magnetic field (magnetic field frequencies higher than 100 kHz) interference, due to the magnetic permeability of ferromagnetic materials with the increase of the frequency decreased, so that the shielding effectiveness decrease, so low-frequency magnetic field shielding can not be used for high-frequency magnetic field shielding. If you won’t use the    cell phone  jammer for a long time, keep it at dry and ventilated places.Current source of high-frequency magnetic interference shielding materials widely used in copper, aluminum and other metal a good conductor. If the high-frequency magnetic field with a metal shell to wrap up the source of interference, its metal shell wall in the eddy current, magnetic field interference source will limit the metal shell, shielding played a proactive role; and high-frequency magnetic field outside the metal shell the same as eddy current role must be to bypass the metal shell, can not enter the metal shell, but also played the role of passive shielding.
Keep the   cell phone blocker at dry and ventilated places to avoid contacting salt mist and harmful gas for a long time. In short, for the magnetic shielding in terms of: 1) When the high frequency electromagnetic interference sources, the use of high conductivity and low resistivity of the metal material in the eddy current generated by the reverse magnetic field, the formation of external electromagnetic waves offset to achieve the shielding the effect.
Actually present or iron shielding materials commonly used in magnetic media. Theoretical basis is that the magnetic field from the low permeability of high permeability media to spread the medium, the magnetic field lines will be the same as the light "refraction", the higher the permeability, the more magnetic field lines tend to medium boundary.    cell phone  jammer   needs no maintenance.We can find the magnetic permeability than air or vacuum high times on the ferromagnetic material, so most of the air in the magnetic field lines into the medium after propagation along the inner surface of the media, the rational design of media forms, it can make the magnetic field lines less able to reach the other side through the media. Magnetic media can not be used as anti-magnetic shielding reason is because all of these media (except superconductors), the diamagnetism is very weak, not enough to offset the external magnetic field.
Magnetic shield design must also take into account the high and low frequency interference sources. For low-frequency magnetic field (magnetic field at frequencies below 100
kHz) interference sources, usually iron, silicon steel, permalloy shielding materials [1,2]. Don’t clean the surface of    cell phone  jammer   with chemical solvent. Shown in Figure 1, is located close to the two parallel wires 1 and wire 2. One pair of wires 2 wire coupling interference of the magnetic field:

Where: M is the distribution of mutual inductance between two conductors, M = Φ/I1; I1 is the current flowing through the wire 1; Φ for the current I1 generated by cross-linking of wire 2 flux. Magnetic field coupling to suppress interference, should minimize the distribution of mutual inductance M, that is, reducing the cross-linked flux Φ [3,4]. Avoid to penetrate water into    cell phone  jammer  .Shielded such interference, the best selection of high-permeability shielding shell made of ferromagnetic material, the circuit will be the source of interference or interference shielding. Ferromagnetic materials, the greater the permeability, the higher the shielding effectiveness; thicker shielding, the shielding effect will be better. Therefore, the actual shielding are often used to improve the performance of multi-layer shielding.