Electromagnetic interference (EMI) impacts electrical circuits as a result of either electromagnetic induction or electromagnetic radiation produced from some external source. The source of the EMI may be any entity that carries fast changing electrical currents, like an electrical circuit, or the Sun. The interference can disrupt, block, or diminish the efficiency of the effected circuit and in some cases, may cause the circuit to fail. In some cases, the failure may result in further downstream losses that can have significant financial or safety implications. For this reason, EMI Shielding has been designed into mission critical devices in industrial machinery, medical, telecommunications, automotive and aerospace industries to protect those devices and circuits.
Switching loads such as those produced by electric motors, transformers, heaters, lamps, ballasts, power supplies, etc., all trigger electromagnetic interference particularly when currents exceed 2Amp. There are common methods used to reduce EMI which allow for modest EMI reduction at minimal currents, however they typically do not work at currents over 2Amp or on loads with electromechanical contacts.
EMI often occurs unnecessarily as a result of poorly designed electronic products, or their components. It regularly affects the reception of AM radio in urban areas. It may also have an impact on cell phone signals, FM radio and television reception, and more importantly it can interfere with industrial machinery controllers, hospital monitoring and communication equipment and in-flight communications between airplanes and traffic control towers.
EMI shielding is now finding its way to more common parts of an electronic device’s or system’s components. EMI shielding is often used in handheld electronic devices to prevent external frequencies near the operating frequency of the device from affecting its use. In hospitals, the FDA has issued standards to prevent equipment, communications and monitoring systems from being affected by electronic devices like cell phone, PDAs, laptops and electronic games. Due to the broad application of EMI shielding, prices for the materials and processing are becoming less expensive, making it even more likely to be used on more electronic equipment in the future.
Electromagnetic shielding reduces the electromagnetic field in a space through the use of barriers made of conductive or magnetic elements. Electromagnetic shielding is normally applied to enclosures to isolate electrical devices from electronic frequencies coming from external sources. Electromagnetic shielding can also be designed to block radio frequency electromagnetic radiation.
EMI shielding helps to reduce the combining of radio waves, electromagnetic fields and electrostatic fields. A conductive enclosure designed to block electrostatic fields may also be called a Faraday cage. Design elements that determine how effective the EMI shielding is, are: the material used to make the shield, material thickness, the dimensions of the shielded volume, the frequency of the magnetic fields and the size, shape and location of openings in the enclosure (which must be small enough to block the targeted wavelength).
Faspro Technologies is a leading supplier of metal EMI shielding used by global companies in the industrial products, medical, telecommunications, automotive and aerospace industries. We specialize in short lead time development projects where our capabilities including engineering, prototyping, and low volume production of EMI shielding can provide the solutions our customers need today.
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