Learn how magnetic fields work, why shielding matters, and how to select the right materials for electromagnetic interference (EMI) control.

What is a Magnetic Field?

A magnetic field is an invisible force generated by magnets, electrical currents, or natural sources like the Earth. The classic iron filings experiment with a bar magnet gives us a glimpse of how magnetic lines flow—from one pole to the other.

Quick Tip: Magnetic fields are strongest closest to their source and weaken with distance. One of the best passive shielding techniques is simply increasing the distance between the source and sensitive equipment.

Magnetic Field Exposure and Shielding Principles

When shielding an object, the volume of magnetic exposure matters. A larger object within the same magnetic field captures more magnetic flux. Even if the field’s strength doesn’t change, the surface area exposed to the field affects how shielding must be designed.

Key Insight: Magnetic fields cannot be blocked—only redirected using high-permeability materials.

Measuring Magnetic Fields

Magnetic fields are measured using:

  • Gaussmeters (for magnetic flux density)
  • Compasses (for DC magnetic direction)
  • Pickup coils (for AC field detection)

Common Units of Measurement

PropertyCGS UnitSI UnitConversion
Magnetic FluxMaxwellWeber1 Wb = 10^6 Maxwells
Flux Density (B)GaussTesla1 T = 10^4 Gauss
Field Strength (H)OerstedA/m1 Oe = 79.577 A/m
Permeability (μ)Gauss/OerstedWb/m-A–

Will a Magnetic Shield Block Field Effects?

No material completely blocks magnetic fields without being attracted to them. However, high-permeability ferromagnetic alloys (like Mu-metal) redirect the field lines through themselves, protecting the sensitive components inside.

These materials concentrate the field inside themselves and reduce field intensity outside the shielded area.

Shielding the Source vs. Shielding the Device

Should you shield the source of the interference or the sensitive device?

Shielding the Source:

  • Requires thicker, often heavier materials
  • Must shield all possible sources

Shielding the Device (Recommended):

  • Protects against current and future interference
  • Easier to implement in most applications

🔧 Try This: DOMADIA Magnetic Shielding Lab Kit offers customizable solutions for DIY and industrial applications.

How to Reduce Interaction Between Two Magnets

Shielding materials are attracted to magnetic fields. If placed between two attracting magnets, the shield pulls the fields in—but doesn’t eliminate the force.

If magnets repel, the field is still redirected through the shield, often pulling the magnets toward the material. Using thicker materials can better isolate or offset the magnetic poles.

RF vs. Magnetic Shielding

Shield TypeFrequency RangeMaterials UsedMechanism
RF Shielding>100 kHzCopper, aluminum, conductive rubberConductivity
Magnetic Shielding<100 kHzHigh-permeability alloysMagnetic permeability
Magnetic shielding can work as broadband EMI shields when designed properly.

DC vs. AC Magnetic Fields

TypeSourceBehavior
DCEarth, permanent magnetsStatic or slowly varying
ACPower lines, electronicsOscillating at 50–60 Hz or more
AC fields are commonly referred to as EMI (electromagnetic interference). Shielding effectiveness differs between static (DC) and dynamic (AC) fields.

Electromagnetic Interference (EMI) Frequency Ranges

EMI TypeFrequency Range
Microwave (MW)300 MHz – 300 GHz
Radio Frequency (RF)300 Hz – 300 MHz
Extremely Low Frequency (ELF)30 Hz – 300 Hz
ELF includes power line frequencies (50/60 Hz), a major source of interference in most environments.

Common EMI Terms Explained

TermMeaning
ELFExtremely Low Frequency magnetic fields (e.g., 50–60 Hz)
EMFElectromotive Force / Electromagnetic Field—describes field strength
EMF ProtectionReducing exposure to magnetic flux using shielding materials

Types of Radiation Shielding Materials

MaterialDescription
MuMetalSoft magnetic iron-nickel alloy ideal for shielding antenna and microwave systems.
EMF RF Shielding FabricsVersatile materials used in clothing and construction to block EM radiation.
EMI Finger Strips (BeCu)Ensure reliable shielding for waveguides, connectors, and enclosures.
TitaniumDurable and biocompatible, used in medical equipment for structural and shielding roles.
High-Temperature CablesFire-safe cables for high-frequency environments in electrical systems.
Beryllium WindowsAllow X-rays to pass while shielding from harmful radiation—used in X-ray machines.
Ultra Thin Metal Foils/FilmsIdeal for microelectronics and antennas, providing effective shielding with minimal weight.
RFID FabricsUsed for RF radiation shielding in both conductive and non-conductive forms.
Copper-Aluminium Bimetal SheetsCombine copper and aluminum benefits for lightweight, effective shielding.
Glass Films (Semi-Transparent/Opaque)Maintain visibility while offering radiation protection for screens and windows.

Learn More with DOMADIA™

DOMADIA offers:

  • Magnetic shielding materials
  • Design guides
  • Product bundles like the DOMADIA Magnetic Shielding Lab Kit

Contact our engineering team to discuss custom EMI protection for your next project.

📞 Get in Touch | 🛠️ Shop Magnetic Shielding Kits

#MagneticShielding #EMIShielding #ElectromagneticInterference #MagneticFields #EMFProtection #RFShielding #MagneticMaterials #MuMetal #ShieldingSolutions #DOMADIA #EngineeringInnovation