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  provides effective shielding for sensitive conductors and power wiring exposed to a wide frequency range, interference environment and internal cross coupling. EMI-Shield has superior attenuation that's effective from the kiloHertz to the gigaHertz frequency range. They assure that your electrical and electronic systems meet specifications relating to electromagnetic interference. Use Calmont's experience as a leader in the development of state-of-the-art EMI products that solve your interference problems. |
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| As shown in Fig. 1, the input signal is interference-free until it comes in contact with the power line magnetic field (or other magnetic field), which then causes a distorted signal in the equipment. |
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Fig. 2 illustrates that copper has very little shielding effect at low frequencies. Calmont's EMI shielding outer braid provides moderate shielding at low frequencies and good shielding at high frequencies. The inner braid, although furnishing less shielding at high frequencies, provides excellent shielding at low frequencies. The end result is a shielding combination that is effective throughout a broad frequency range. |
| Electromagnetic frequency shielding provides protection for the input signal that is susceptible to magnetic field induction, as well as to electrical fields, until the signal is safely within the desired electrical or electronic equipment, as ia illustrated in Fig. 3. |
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As illustrated in Fig. 4, a cable whose conductors are to be protected from an external source of EMI has an outer low permeability shield braided over a high permeability shield. The incident radiation of external EMI strikes the outside surface of the outer shield (the first boundary reflection loss area) where some of the radiation is reflected. The radiation then penetrates into the material, where absorption takes place. | ||
| The second reflection loss occurs at the inside surface of the outer
shield (the second boundary reflection loss area). If the radiation is strong enough,
it will proceed through this outer shield to the outside surface of the inner shield (the
third boundary reflection loss area) where more of the reduced radiation is
reflected. From there, it proceeds to the fourth boundary reflection loss area (the
inside surface of the inner shield), during which time some of the radiation becomes
absorbed into the inner shield material. If the shielding is to be utilized to prevent electromagnetic interference from signals present in wires, then the inner layer should be of low permeability braid and the outer layer of high permeability braid. Shields can also be configured with a low permeability shield on the inside and out with with high permeability shields in between. In any event, the low permeability shield should always be closest to the source of interference. |
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Click here for Calmont's Product Catalog. |
