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Superior protection against high frequency environmental noise

Environmental noise is comprised of magnetic and electric fields. Magnetic field coupling occurs only at low frequencies (i.e. 50 Hz or 60 Hz) and its impact can be ignored for all types of balanced cabling. Electric fields, however, can produce disturbing signal voltages on balanced cables. The magnitude of the voltage induced can be modeled assuming that the cabling system is susceptible to interference in the same manner as a simple loop antenna. Loop antenna models demonstrate that screened and fully-shielded cables offer 100 to 1,000 times the immunity protection from electric fields than UTP cables do!

Solid aluminum foil is the preferred shielding media for telecommunications cables because it provides 100% coverage for high frequency (i.e. greater than 100 MHz) applications, as well as low electrical resistance. The thickness of the foil shield is selected so that 30 MHz and higher frequency signals cannot penetrate the shield. This design approach ensures that higher frequency signals will not be able to penetrate the foil shield and lower frequency signals will not interfere with the twisted-pairs due to their good balance performance.

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