The cell phone jammer is a domestic initiation

Here, the low-frequency magnetic field shielding is generally below 100kHz. Located close to the two parallel wires 1 and wire 2. One pair of wires 2 wire magnetic coupling interference as: U2 = jωMI1 where: M is the distribution of mutual inductance between two conductors, M = Φ/I1; I1 is the current flowing through the wire 1; Φ is current; I1 produced on the wire 2 cross-linked flux. Magnetic field coupling to suppress interference, should minimize the distribution of mutual inductance M, that is, to reduce interference between the source and the receiver circuit of cross-linked flux Φ. People can use the battery of cell phone jammer when it is charged.Shielding measures such interference shielding, suggested the use of high permeability shielding shell made of ferromagnetic material, the source of interference shielding, so that the magnetic flux generated by the source of interference can be directed to the ferromagnetic material, and thus not be interfere with the circuit cross-linked. Similarly, it can be circuit interference shielding. The shielding shell production, should note the following: 1. The choice of materials, the smaller the better magnetic reluctance Rm Rm = L / μS (L is the length of the magnetic circuit; for the magnetic cross-sectional area; S μ as a guide magnetic ratio). Selection of high-μ values of iron, silicon steel, permalloy, etc.; 2 in the shielding shell design, the shell should be thick enough to increase S, increase the shielding effect to the purpose; in the direction perpendicular to the magnetic flux can not open, so as not to increase the reluctance; 3 in order to better improve the shielding effect, and sometimes the use of multi-layer shielding, installed shielding shell should pay attention to tighten.The cell phone jammer is a domestic initiation. 2.3.2 High-frequency magnetic field shielding frequencies above 100kHz high-frequency magnetic field shielding is the use of electromagnetic induction shielding shell surface in the vortex generated by the anti-magnetic field to achieve their goals. The ferromagnetic materials at high frequencies, the magnetic loss is too large, is not conducive to the formation of the shielding shell as large eddy, fail to effectively eliminate high-frequency magnetic interference purposes. Made a good conductor shielded shell shield for an electronic circuit equivalent circuit. With the cell phone jammer, you never worry to be stalked.L is the inductance of the electronic circuit; M shell shielding for electronic circuits and mutual inductance; Ls is the inductance shielding shell; I for the electronic circuit of the current; Rs is the resistance shielding shell. Which can be drawn on the formation of eddy current shielding shell is: When the frequency is high, ωLs>> Rs, Rs can be ignored at this time, you can simplify Is ≈ MI / Ls when the frequency is low, ωLs <<Rs, this when ωLs negligible, can be reduced to Is ≈ jωMI / Rs shield measures 1 vortex increases with the frequency increases, indicating that high-frequency magnetic shielding should be used in conductive materials. (2) At higher frequencies, eddy size and frequency-independent, that is increased with frequency eddy current increases to a certain extent, continues to rise the frequency of its shielding effect is no longer enhanced. The cell phone jammer is your patron saint from being stalked.3 in the low frequency, ω low, Is small, the shielding effect is poor; Rs small, Is a large, shielding effect, shielding and less wear and tear, which requires selection of a good conductor shielding materials. As the high-frequency skin effect, eddy current shielding shell surface only in the thin layer flow, therefore, in the design of high-frequency shielding shell, the shell with different low-frequency shielding, without doing very thick, just to ensure a certain degree of mechanical strength can, generally 0.2 ~ 0.8mm.