Final answer:
Magnetic fringe fields are stray magnetic fields from an MRI magnet that can affect nearby electronics, combated with active shielding. MRI magnets create strong fields necessary for imaging, affecting antenna design. Magnetic shielding can protect against these fields much like a Faraday cage with electric fields.
Step-by-step explanation:
Magnetic fringe fields are the stray magnetic fields that extend beyond the confines of the magnet itself, such as those produced by an MRI scanner. To combat the effect of these fields, which can affect nearby electronic devices and become a safety concern, a special type of MRI magnet design is used. This design is called active shielding. Active shielding employs additional coils that produce magnetic fields to counteract the fringe fields, thereby reducing their extent and impact outside the MRI machine. In an MRI machine, the function of magnets is crucial as they create a strong, stable magnetic field necessary for the imaging process. High magnetic fields allow for clearer and more detailed images but using them requires the use of higher frequency radio waves. Higher magnetic fields influence the design of antennas, favoring smaller antennas which can handle the higher frequencies necessary for transmitting the radio waves in the MRI scanner. Magnetic shielding, similar to a Faraday cage effect for electric fields, is possible. Such magnetic shielding is useful in MRI facilities to protect the surrounding environments from the magnetic fields of the MRI scanner, making the surrounding areas safer and preventing interference with other electronic equipment.