RFI Shielding
Radio frequency interference, or RFI, is radiated electromagnetic "noise" which travels through the air as radio waves. RFI is identical to EMI, or electromagnetic interference, except that EMI is conducted along wires, electrical circuits and conductors, while radio frequency interference (RFI) travels across "free" air space in the form of radio waves. Electromagnetic interference and radio frequency interference are the magnetic fields which are given off as a bi-product of electrical currents, and both EMI and RFI impede the normal flow of electricity through currents, causing interference and malfunction in electronic devices. Radio frequency interference is high frequency, typically 100 kilohertz or above; RF shielding is especially designed to block these high frequencies with copper, aluminum, galvanized steel, conductive rubber, plastic or EMI coating paints. RFI can be shielded by EMI enclosures, EMI coatings and EMI gaskets. It should be noted that not all of these block ground-conducted electromagnetic interference; EMI enclosures, gaskets and EMI coated enclosures aim to block out RFI signals traveling through the air and are not nearly as effective in trying to block conducted EMI.
EMI and RFI are created, by widely varying degrees, by everything which conducts electrical energy, including electrical wires, electrical appliances, computers and all electronic equipment. Signal-bearing electronic devices such as mobile phones, laptops and GPS devices give off RFI. Normal electrical currents are disrupted when moderate to high levels of EMI or RFI are introduced; unchanneled electromagnetic signals and radio frequency waves can act as "noise", magnetically altering normal flow of electrical currents and impeding the flow of electrical energy. EMI enclosures, coated interiors and gaskets are necessary to provide full protection from RFI, which continues to increase exponentially as more and more mobile electronic devices are introduced to the consumer market.