Especially when using high-speed data networks, the time required to intercept large amounts of information is significantly lower than the time required to intercept low-speed data transmissions. The twisted pair in the data twisted pair can resist external interference and inter-pair crosstalk through its own twisting at low frequencies, but at high frequencies (especially when the frequency exceeds 250MHz), only twisting cannot achieve anti-interference For the purpose, only shielding can resist external interference.
The cable shield acts like a Faraday shield. Interfering signals enter the shield, but not the conductors. Therefore, data transmission can run without problems. Since shielded cables have lower radiated emissions than unshielded cables, network transmission is prevented. Shielded networks (shielded cables and components) significantly reduce the radiated levels of electromagnetic energy that could be intercepted as it enters the surrounding environment.
Shielding options for different interference fields mainly include electromagnetic interference and radio frequency interference. Electromagnetic interference (EMI) is primarily low frequency interference. Motors, fluorescent lights, and power lines are common sources of electromagnetic interference. Radio frequency interference (RFI)) refers to radio frequency interference, mainly high frequency interference. Wireless communications such as radio, television broadcast, and radar are common sources of radio frequency interference. For EMI immunity, braided shielding is the most effective
because it has a lower critical resistance; for radio frequency interference, foil shielding is most effective. Since braided shielding depends on the change of wavelength, the gap generated by it allows high-frequency signals to freely enter and exit the conductor; for high and low frequency mixed interference fields, the combined shielding method of foil layer and braided mesh with broadband coverage function should be used. Generally speaking, the higher the mesh shielding coverage, the better the shielding effect.
