Magnetic Field Shielding:
Solutions for static and low-frequency fields

Magnetic fields cannot be turned off, but they can be directed in a targeted manner. Using highly permeable materials, we reroute magnetic fields around sensitive areas instead of allowing them to pass through. This protects people, equipment, and measurement results from interference caused by transformers, high-voltage power lines, railway facilities, or strong magnets such as MRI systems. We design, manufacture, and install each shielding solution individually at our facility in Hennef.

Each magnetic field shielding system is individually tailored to the field strength of the respective MRI system, the technical requirements of the MRI manufacturer, and the structural constraints, as magnetic geometry, stray field distribution, and technical requirements vary by manufacturer. Because we handle both design and manufacturing in-house, we can implement project-specific modifications quickly and ensure quality throughout the entire manufacturing process. We take future upgrades and the system’s lifecycle into account as early as the planning phase.

What is electromagnetic field shielding?

Magnetic field shielding reduces the strength of magnetic fields within a defined area. Unlike RF shielding, which reflects electromagnetic waves, the magnetic field is absorbed by a material with high magnetic permeability and redirected around the space to be protected. The two methods are not mutually exclusive: In many projects, we combine magnetic field shielding with RF shielding, such as in MRI booths, where both radio frequency and the static stray field of the magnet must be controlled.

Schwarz develops coordinated magnetic field and RF shielding systems and, when necessary, integrates both systems into a single modular enclosure design. This reduces the number of interfaces and results in technically optimized comprehensive solutions.

Static and Low-Frequency Fields

We distinguish between two field types:

Static fields (DC):
These are generated by permanent magnets or magnetic resonance imaging (MRI) scanners. Materials with high saturation flux density, such as pure iron or transformer steel, are used here.

Low-frequency alternating fields (AC/LF)
These fields are generated by power lines, transformers, or busbars. Mu-metal is particularly well-suited for these fields, as it achieves high permeability even at low field strengths.

Comparison of Materials

Material
Mu-metal
Electrical steel (silicon-iron)
Pure Iron / Transformer Steel
Galvanized sheet steel

Field Type
low frequency (AC/LF)
Low-frequency, moderate field strengths
static (DC)
static and low-frequency

Features
Very high permeability, sensitive to deformation, saturates more quickly at high field strengths
durable, economical, ideal for large areas
High saturation flux density, mechanically stable
combines mechanical stability with effective shielding

Typical Applications
Laboratory booths, electron microscopy, precision measurement technology
Room and Cabin Shielding
MRI Scatter Field Shielding, Strong Permanent Magnets
Modular design, combined RF and magnetic field chambers

The choice of material depends on the field strength, frequency, and the required residual field. We determine this together with you during the planning phase, often using a combination of several materials in a multilayer structure.

Modular Integration of Magnetic Field Shielding
Material selection is project-specific and takes into account field strength, residual field, MRI manufacturer, structural constraints, and cost-effectiveness. The goal is to achieve the technically and economically optimal solution.

Magnetic Field Shielding for MRI:
Stray Field Shielding for MRI Sites

A magnetic resonance imaging (MRI) scanner generates a strong static magnetic field that extends far beyond the actual examination room. Compliance with the 5-gauss limit (500 µT) is required by law in publicly accessible areas; this is the threshold for people with implants such as pacemakers. At the same time, external interference fields from the surrounding environment—such as those generated by transformers, elevators, or railway equipment—can impair image quality by causing artifacts.

For both directions, we install stray-field shielding made of pure iron or transformer steel, tailored to the field strength of the respective MRI system (1.5T, 3T, or 7T) and the on-site structural conditions. MRI magnetic field shielding is therefore a separate trade from the RF booth and is incorporated into the planning from the outset in both new construction and renovation projects.

We carry out projects across the entire magnetic field strength spectrum, from standard MRI systems with 1.5 T or 3 T to high-field and research systems with 7 T or 9.4 T. Since magnetic geometry and scattered field patterns vary depending on the MRI manufacturer, manufacturer-specific requirements are incorporated into the planning process from the very beginning. For large-scale projects, we have already installed up to 800 metric tons of magnetic shielding material. Our experience in materials logistics, installation, and project coordination ensures that even complex projects run smoothly.
You can find more information about MRI projects and our references on the Medicine page.

Other Areas of Application

Complete shielding from a single source

Research

Magnetically shielded laboratory rooms and booths for electron microscopy, SQUID measurements, EEG, and EMG, as well as other highly sensitive measurement and testing environments where even the slightest field fluctuations can distort measurement results.

Industry

Protection of sensitive equipment and measurement technology located near substations, high-voltage power lines, or railways, including when integrated into modular room-in-room systems.

Reference Projects

Projektbild zu New installation of a HF cabin

Siemens AG

New installation of a HF cabin

Period: 2007
MRT: Siemens MAGNETOM 7,0 Tesla
Magnetic shielding: 250 t – Stahlblech ST37
Material: Aluminium, material thickness d= 3.0 mm thick
Dimensions HF cabin:: 16.98 m x 7.31 m x 5.85 m (L x W x H)
Dimensions revision cabin:: 5.36 m x 3.41 m x 1.30 m (L x W x H)
Special features: Raised floor inside the HF cabin

Foundation plate to hold the Fe-screen (250 t) and the magnet weight (32 t)

Complete interior fittings consisting of interior wall panelling, false ceiling and lighting.

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Siemens AG

New installation of a HF cabin with magn. Shielding

Period: Mitte 2012
MRT: Siemens MRT 7,0T
Magnetic shielding: 5,2 t – Stabolec 270/50A
Material: Aluminium, material thickness d= 3.0 mm thick
Dimension: 11,81 x 5,28 x 4,12 m (L x B x H)
Special features: 2 pieces special filter plate for customer equipment

Projector tube feed-through for beamer incl. adapted furniture

Raised floor inside the HF cabin including floor cable duct

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Siemens AG

New installation of a HF cabin with magn. Shielding

Period: Mitte 2012
MRT: Siemens Magnetom Trio 3T anschl. Umrüstung Prisma 3T
Magnetic shielding: 7 t – Stabolec 270/50A
Material: Aluminium, material thickness d= 3.0 mm thick
Dimension: 7,32 x 4,30 x 3,15 m (L x B x H)
Special features: 2 pieces special filter plate for customer equipment

Floor cable duct inside the cabin floor

Projector tube feed-through for beamer incl. adapted furniture

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Siemens AG

New installation of a HF cabin with magn. Shielding

Period: Februar 2012 - Mai 2013
MRT: Siemens Magnetom 9,4 Tesla
Magnetic shielding: 610 t – magnetische Abschirmung aus Stahlblech ST37
Material: Aluminium, material thickness d= 3.0 mm thick
Dimensions:: 17.20 x 11.00 x 6.80 m (L x W x H)
Dimensions attached technical cabin:: 10,65 x 2,60 x 1,65 m (L x W x H
Special features: 3 pieces HF shielding doors in different dimensions

raised floor

over 100 LED spotlights

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Siemens AG

New installation of a HF cabin

Period: 2006
MRT: Siemens MAGNETOM 7,0 Tesla
Magnetic shielding: 426 t – Stahlblech ST37
Material: Aluminium, material thickness d= 3.0 mm thick
Dimensions HF cabin:: 11.58 m x 6.78 m x 5.14 m (L x W x H)
Dimensions revision cabin:: 4.38 m x 3.41 m x 1.54 m (L x W x H)
Special features: Raised floor inside the HF cabin

Foundation plate to hold the Fe-screen (426 t) and the magnet weight (38 t)

Complete interior fittings consisting of interior wall panelling, false ceiling and lighting.

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Siemens AG

New installation of a HF cabin

Period: Juli/August 2011
MRT: Siemens Biograph mMR 3.0T
Magnetic shielding: 4,42 t – Stabolec 270/50A (magnetische Abschirmung)
7,50 t - Blei-Abschirmung d=5,0 – 8,5 mm
Material: galvanised sheet steel, material thickness d= 2.0 mm thick
Dimension: 7,53 x 4,91 x 3,00 m (L x B x H)
Special features: LED spotlight for room illumination

Special filter plate with extensive internals

Projector tube feed-through for beamers

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Projektbild zu New installation of a HF module cabin

Siemens Niederlande

New installation of a HF module cabin

Period: August 2010
MRT: Siemens Magnetom Skyra 3,0 Tesla
Magnetic shielding: Typ Stabolec 270/50A (2,819 to.)
Material: Aluminuim, material thickness d= 3,0 mm thick
Dimension: 7.685 x 4.835 x 3.000 mm (L x B x H)
Special features: V2A stainless steel foundation under the MRT for structure-borne sound decoupling (2,000 x 2,000 x 70 mm)

2,819 to. magnetic shielding type Stabolec 270/50A

6 LED light bars RGB in cabin wall, L= 1,00 m

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Radiologische Gemeinschaftspraxis

New installation of a HF module cabin

Period: 2011
MRT: Siemens Magnetom Espree 1.5 Tesla
Magnetic shielding: Typ Stabolec 270/50A (3,015 to.)
Material: Aluminuim, material thickness d= 3,0 mm thick
Dimension: 7.535 x 4.010 x 2.700/2.720/2.870/2.925 mm (L x B x H)
Special features: 3 pieces HF shielding doors in different dimensions

height and size optimized HF cabin

to the situation on site (columns and beams)

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Praxis

New installation of a HF cabin

Period: Juli 2012
MRT: General Electric Optima MR430s 1.5 T
Material: Aluminium, material thickness d= 3.0 mm thick
Dimension: 3,63 x 3,30 x 2,85 m (L x B x H)
Special features: Interior wall cladding i. B. of the rear wall in "Limone" colour

remaining walls in white with "Limone" connecting springs

LED spotlight for room lighting

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General hospital Vienna, Austria

Beitragsbild zu University Maastricht - 7 Tesla, Netherlands

Maastricht University Netherlands

Beitragsbild zu University Maastricht - 3 Tesla, Netherlands

Maastricht University Netherlands

Beitragsbild zu University Maastricht - 9.4 Tesla, Netherlands

Maastricht University Netherlands

Beitragsbild zu University Hospital, Essen 2

University Hospital Food

Beitragsbild zu University Hospital, Essen

University Hospital Food

Hospital in Nijmegen Netherlands

Radiological joint practice St. Augustin, Germany

Beitragsbild zu Radiological practice Halle

Radiological practice Halle a. d. Saale

How does a project work at Schwarz Shielding?
After receiving the inquiry, we analyze the on-site conditions based on the MRI manufacturer’s planning and calculations. Based on this, we design the shielding, manufacture the components in Hennef, and handle the assembly and acceptance testing. Throughout the entire project, you will have a dedicated point of contact who will coordinate planning, manufacturing, installation, and project partners. This way, you can keep track of the project’s status at all times.

FAQ

Which material shields against magnetic fields?

Ferromagnetic materials such as Mu-metal, pure iron, and electrical steel are the most effective. While non-magnetic metals like aluminum or copper can shield high-frequency fields, they provide virtually no shielding against static or low-frequency magnetic fields.

Is it possible to completely shield against magnetic fields?

Complete shielding is physically and economically virtually impossible to achieve. In practice, reducing the field to the required limit—such as the 5-gauss line in MRI facilities—is both realistic and sufficient.

What is the difference between magnetic field shielding and RF shielding?

RF (radio frequency) shielding blocks electromagnetic waves through reflection, typically using conductive materials like aluminum or steel. Magnetic shielding redirects static and low-frequency magnetic fields around the protected area using highly permeable materials. Many projects, such as MRI cabins, require both.

How strong does MRI magnetic field shielding need to be?

This depends on the field strength of the MRI system and the structural conditions of the building. The primary goal is usually to maintain the 5-gauss line in public areas, though research environments may require significantly lower residual field values.

Does every MRI machine need to be magnetically shielded?

Not every MRI system strictly requires additional magnetic shielding. Whether shielding is necessary depends on the system’s field strength, the layout of the building, and the distance to publicly accessible or sensitive areas. Shielding becomes necessary if the legally required 5-gauss limit cannot be maintained without structural measures, or if external fields interfere with image quality.

Can magnetic field shielding be adjusted later?

Yes. Thanks to modular design, existing magnetic shielding can often be adapted or expanded during modernizations or MRI equipment replacements—frequently without having to open up the building’s structural framework.

What role does the MRI manufacturer play in the planning process?

Magnet geometry and stray field distribution vary depending on the MRI manufacturer. These manufacturer-specific requirements are integrated into the design of the shielding right from the start of the planning phase.

Are you planning a new MRI project or the modernization of an existing system?  Our experts will support you from the initial idea through to successful commissioning.  Request a project quote, schedule an appointment, or call us directly.

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Magnetic Field Shielding:Solutions for static and low-frequency fields

What is electromagnetic field shielding?

Static and Low-Frequency Fields

Comparison of Materials

Magnetic Field Shielding for MRI:Stray Field Shielding for MRI Sites

Other Areas of Application

Reference Projects

New installation of a HF cabin

New installation of a HF cabin with magn. Shielding

New installation of a HF cabin with magn. Shielding

New installation of a HF cabin with magn. Shielding

New installation of a HF cabin

New installation of a HF cabin

New installation of a HF module cabin

New installation of a HF module cabin

New installation of a HF cabin

FAQ

Magnetic Field Shielding:
Solutions for static and low-frequency fields

Magnetic Field Shielding for MRI:
Stray Field Shielding for MRI Sites