The Vanguard System RF enclosure is basically a Faraday cage constructed of panels of high-quality copper foil wrapped round wooden frames, which are clamped together such as to ensure the integrity of the shielding throughout the life of the enclosure. Electrical cables, medical gas pipes and other supplies are routed out of sight in the wall cavities. This method of construction gives the architect full freedom of design and permits subsequent replacement or modification of the MRI equipment. If necessary, with the exception of the floor, the enclosure can be dismantled and erected at another location. All fittings are of non-magnetic materials. Doors, windows and penetrations for services are also shielded or fitted with filters to prevent leakage. RF enclosures are dielectrically insulated from the rest of the building. They are delivered to site in prefabricated modules and assembled by trained Vanguard System personnel.

The following excellent attenuation figures are typical values which vary according to the MRI equipment in use:

Field	Frequency	Attenuation
Magnetic field	15 MHz	100 dB
Electric field	10 MHz	100 dB
	30 MHz	100 dB
Plane Wave	30 MHz	100 dB
	100 MHz	100 dB
	200 MHz	100 dB