All About Shielding FAQs


Frequently Asked Questions - EMI Shielding

How Do Magnetic Shields Work?

What Is A Magnetic Field?

Magnetic Fields And Shields Overview?

How Do You Measure Magnetic Fields In Gauss?

What Is Magnetic Permeability?

What Do We Mean By A Ferromagnetic Material Being Magnetically Soft?

Will A Magnetic Shield Block The Fields Effects?

Does Cutting The Alloy Destroy Its Properties?

Should The Source Of Interference Or The Sensitive Device Be Shielded?

What Are The Issues Using Magnetic Shielding Material At High Vacuum?

What Effect Does Heating The Magnetic Material Have on its Magnetic Shielding Properties?

What Effect Does Cryogenically Cooling The Magnetic Material Have on its Magnetic Shielding Properties?

Why Do MuMETAL® and Co-NETIC® Not Perform at Cryogenic Temperatures?

How Can I Shield One Magnet So It Doesn't Interact With Another That is Close By?

What Are The Frequency Ranges Of Electromagnetic Inteference (EMI) And Electromagnetic Compatibility (EMC)?

What Is The Difference Between DC And AC Fields?

What Is The Differernce Between RF And Magnetic Shielding?

Why Are Both The Ferrite NETIC® S3-6 And The Nickel Alloy Co-NETIC® AA Offered?

Why Is Co-NETIC® AA Alloy Offered In Both Perfection Annealed And Stress Annealed Types?

What Is MuMETAL®?

Why Is MuMETAL® Offered?

Why Must MuMETAL® Alloy Be Final Annealed to Develop Magnetic Shielding Performance?

Magnetic Shield Slide-Rule Calculator Problem-Solving Examples?

What Are The Manufacturing And Design Considerations For Fabricating Shielding?

Magnetic Shielding Realities?

What Do You Suggest To Shield A Room?

How Do I Measure A Magnetic Field With An EP Probe?

INTER-8® Weave Cable VS. Conventional Twisted-pair Cable?

What Do You Offer In Mica?

Where May I Get A Copy Of Magnetic Shield's ISO Certification?

How Do I Use The Single Axis AC Magnetic Field Meter #EF-401? (Plus Specs & Functions)


Glossary of Shielding Terms

Annealing: The treatment of a metal, alloy, or other material by heating to a predetermined temperature, holding for a certain time, and then cooling to room temperature.

Attenuation: A ratio used to measure the effectiveness of a given shield. The ratio is expressed as the field strength at a given point vs. the resulting field strength at the same point with a magnetic shield in place. A shield which provides a reduction of 100 times has an attenuation of 100:1.

Coercive Force: The magnetic force necessary to demagnetize a substance. Also called coercivity.

Curie Point: Temperature at which magnetism changes; the temperature at which in some substances, such as iron, there is a change in the magnetic characteristics, from ferromagnetic to paramagnetic behavior.

D/C Field: A magnetic field that is non-varying, or perhaps slowly changing. DC fields might be from the Earth, a permanent magnet, or a coil carrying direct current.

Electromagnetic Field (EMF): A field of force associated with a moving electric charge and consisting of electric and magnetic fields that are generated at right angles to each other.

Electromagnetic Interference (EMI): Interference caused by the radiation of an electric or magnetic field.

ELF: Stands for Extremely Low Frequency usually referring to magnetic fields at 0.5 to 100 Hertz.

Ferromagnetism: strong magnetization induced by weak field: a property of some substances, including iron and some alloys, in which application of a weak magnetic field within a certain temperature range induces high magnetism.

Ferromagnetic: With the property of ferromagnetism. Iron, cobalt, and nickel are ferromagnetic metals.

Flux: The strength of a magnetic field represented by lines of force. Symbol f

Frequency: The frequency of a magnetic field, measured in cycles per second (Hz), is usually the same as the operating frequency of the field's source.

Gauss: The number of magnetic lines of force (flux) emitted per square centimeter.

Induction: Refers to magnetic lines of force….see Magnetic Flux Density.

Magnetic Field Strength: Describes the intensity of a magnetic field in free space*. (*at some distance from its source)

Magnetic Flux Density: Describes the concentration of magnetic lines of force in a material.

MuMETAL®: A registered trade name for a high-permeability alloy used for magnetic shielding. It is made up of 80% nickel, 15% iron, and a balance of other metals depending upon the particular formula.

Paramagnetic: Used to describe a substance that is weakly magnetized so that it will lie parallel to a magnetic field.

Permeability: Refers to a materials ability to attract and conduct magnetic lines of flux. The more conductive a material is to magnetic fields, the higher its permeability.

Oersted: A unit (symbol Oe) of magnetic field strength. It is equal to a force of one dyne acting upon a unit magnetic pole in a vacuum.

Saturation: The limiting point of a material to conduct additional lines of flux. The saturation and permeability characteristics of most ferromagnetic materials are inversely related, therefore the higher a material's permeability, the lower its saturation point.

Shield: Something that serves as protection or acts as a defense.