What is Shielding: Definition and 155 Discussions

In electrical engineering, electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. Shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. Electromagnetic shielding that blocks radio frequency (RF) electromagnetic radiation is also known as RF shielding.
The shielding can reduce the coupling of radio waves, electromagnetic fields, and electrostatic fields. A conductive enclosure used to block electrostatic fields is also known as a Faraday cage. The amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of holes in a shield to an incident electromagnetic field.

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  1. N

    Magnetic shielding using a semiconductor?

    I read an article a week or so ago talking about using a semiconductor to disrupt a magnetic field. Generally a magnetic field can be disrupted by any magnetic material in its path. Steel for a basic example can reduce the realized field on the opposite side from the magnetic field source...
  2. A

    What is a preferable shielding

    What kind of materials are suggested to shield an alpha particle, beta particle, and neutron particle? Or is it energy depended? Will particles just get bounced off / deflected sometimes if a wrong material is used.
  3. G

    What is the Debye Shielding Problem?

    Homework Statement Consider a positive point charge +q, immersed in plasma. Show that the net charge in the Debye shielding cloud exactly cancels the test charge. Assume the ions are fixed and that e*phi <<< kTe. Homework Equations f(u) = A exp [-(1/2*m*u^2 + q*phi)/k_b*T_e] u is the...
  4. G

    Plasma Physics Debye Shielding

    Homework Statement Consider a positive point charge +q, immersed in plasma. Show that the net charge in the Debye shielding cloud exactly cancels the test charge. Assume the ions are fixed and that e*phi <<< kTe. Homework Equations f(u) = A exp [-(1/2*m*u^2 + q*phi)/k_b*T_e] u is the...
  5. F

    Using magnetic fields in place of heat shielding

    Using Magnetic Fields in Place of Heat Shielding Joshua “FireStorm” King Note: All Graphs are in SI base units Note 2: I strongly recommend downloading the document version of this post as the equations are actually readable there. RTF Format: Docx Format: Introduction: The Problem I'm a real...
  6. M

    Shielding from electric/magnetic field using a metal box

    Can electric fields can be completely shielded using a metal box or metal sphere, please clarify the concept.
  7. T

    Resonance Self Shielding Correction Definition

    Hello, I was hoping that someone might be able to provide a definition for the "resonance self shielding correction". -TP
  8. C

    Elementary questions on biological shielding in nuclear submarines

    I'd be grateful to be pointed to some elementary information on the biological shielding in nuclear submarines. (Searching the web did not turn up what I was seeking). I understand that the reactor is somewhere near the centre of the sub, with shielding bulkheads fore and aft of the...
  9. T

    Comparing Results of MCNP vs Geant4 for Shielding Design

    I'm curious if anyone has any opinions in the results from MCNP vs Geant4 for shielding design. I like that Geant4 uses a more modern syntax, but iv'e also heard that MCNP gives better results.
  10. G

    Magnetic Shielding: Experiment Materials Available?

    i am attempting an experiment and was wondering if there were any readily available materials that can effectively shield from the effects of magnetism?
  11. P

    Noise Shielding by Rear-Mounted Engines on Aircraft

    How is the noise sheilding provided by the fuselage when the engines are mounted at the rear end of the aircraft ? for example-SAX 40
  12. W

    Conducting Sphere shielding an electric field

    Conducting Sphere "shielding" an electric field Hello. I have a question regarding a problem that I have seen printed many times in various books and which I saw on a test today: A hollow conducting sphere contains 2 charges, q_1\;and\;q_2 . Outside the sphere are two additional charges...
  13. L

    Levitating Magnet with Load of 12oz: Shielding Electronics & Transmitter

    So basically i have this powerful electromagnet that generates an electromagnetic field that can levitate another magnet and withhold a load of 12oz and still levitate: My problem is, I want to be able to use electronics and send wireless signals through this strong magnetic field. I can...
  14. C

    Why Isn't Nitrogen Commonly Used as a Shielding Gas in Welding Instead of Argon?

    Why don't they use nitrogen for welding instead of argon . Unless it does something to the metal . Nitrogen seems like it would be cheaper than argon .
  15. C

    Of shielding and apertures and seams

    Of shielding and apertures and seams... I am working on a project that deals with the 400 MHz RF source that is interfering with a diagnostic device close to it which is a complete DC circuit. Shielding with thin copper is suggested. Read the theory behind the influence of apertures and...
  16. bcrowell

    E.p. implies no gravitational shielding?; Feynman?

    I seem to recall that Feynman had a nice discussion somewhere, possibly in the Feynman lectures, of why there is no such thing as gravitational shielding. IIRC it appealed to the microscopic picture of a Faraday cage and the purely attractive nature of the gravitational force. I can't seem to...
  17. S

    Specialization: radiation shielding and reactor materials

    Is specialization in radiation shielding and reactor/reactant materials a valid area of specialization? I am just worried if the two areas are too broad or different to name as my area of specialization. I ask this because I am trying to answer my applications for area of specialization and I...
  18. K

    Magnetic Field Shielding

    Homework Statement Consider a uniform B_{0} in the z direction, into which a hollow sphere is placed. If the sphere is made of a material with a high permeability (B = \mu \ H), the magnetic field inside will be greatly reduced. Calculate the magnetic field inside the sphere and the maximum...
  19. A

    Do shielding materials get excited and start reactions?

    In neutron activations, target materials are being beamed by high energy flux, thus making the target materials excited and undergo radioactive decay. Neutron analysis then can be performed after the materials are "cool" enough by placing inside the hood with enough shielding. My question is...
  20. A

    Question about neutron shielding and resonance integral

    I have two nuclear engineer related questions, please bear with me. 1. Why is hydraulic material (like water) is good to shield against neutrons? Why not high Z material like lead? 2. In cross section vs. energy of the nuclei, the curve of the graph undergoes 1/E relationship until it hits...
  21. T

    Magnetic shielding, or field line redirection - why does it work ?

    Could someone please explain how magnetic shielding works ? (not superconductors - the mu metal type) Most of the explanations on the site talk about a material with high permeability providing an 'easier path' for magnetic field lines to pass through than the surrounding space, so reducing...
  22. W

    Magnetic Shielding for Electronics Circuits

    Hi All, A conductor cannot shield a circuit against a magnetic field as it does for an electric field. When used in this fashion, the conductor is called a faraday shield. In an electronics circuit, do the induced magnetic fields pose a problem and, if so, how are they handled? Thank...
  23. G

    2 Neo magnets with some Mumetal shielding

    Hi guys I have a simple question. The attached picture shows 2 Neo magnets with some Mumetal sheilding between the magnets. Let's say the gap between the shield and the magnets is 2mm. So the overall distance between the magnets is 4mm. will the magnets still repel from the shielding...
  24. P

    Shielding Effect: What Is It & How Does It Work?

    What actually is shielding effect ?? In particular my book says that the size of Ga is smaller than Al because of poor shielding effect of d electrons , but what is this shielding effect , imean how does it work?
  25. D

    Conductor shielding in electrostatics

    Homework Statement Use Gauss' theorem (and the fact that the line integral of the electric field around a closed loop is zero, if necessary) to prove that a closed, hollow conductor shields its interior from fields due to charges outside. (This is 1.1b in Jackson, and it's not really homework...
  26. I

    EM Shielding Dilemma: Understanding Transverse Wavelengths

    In the classical picture of an electromagnetic wave, the wavelength is specified along the direction of travel. However, with EM shielding that is using a grid (microwave, chicken wire), I've heard that so long as the spaces are less than the wavelength, you will achieve electromagnetic...
  27. S

    Exploring the Possibility of Volcano Shielding: Could it Work?

    Take Yellowstone for example, we do not know when it will erupt again, but we know sometime in the future that it will. We theorize that its driven from a stationary hotspot system which remains stationary as the Earth's upper crust continually slides over it until a weak spot or a spot of the...
  28. D

    Question regarding wind loading and shielding effects on a structure.

    I have come unstuck in my coursework project, and cannot find any information/equations for the effects of shielding on wind loading in a structure (This is not an ordinary structure, it is an unsymmetrical sculpture made up of circular and Universal beams). So i would firstly like to find how...
  29. H

    Magnetic Shielding for 3-Axis Test Equipment

    i am designing a 3-axis test equipment to test the sensitivity of a magnetic sensor. i need to use three axis motorized slides to move the magnetic probe along the three axis. but the magnets present in the motors interfere with the magnetic field of the magnetic probe. is there anyway i can...
  30. E

    Shielding Effect and Chemical Shift

    Homework Statement Given a molecule of chloroethene (vinyl chloride) or ClCH=CH2. Rank the hydrogen atoms in the molecule in terms of which will have the greatest chemical shift. Homework Equations None The Attempt at a Solution Since the Cl and the double bond are both...
  31. G

    Photon buildup in shielding

    Who do you believe? I'm doing some shielding calcs for Cs-137 (662 KeV gamma) in stainless steel (Fe seems close enough) with ux (mfp) in the range of 5 to 15. Shultis and Faw in Radiation Shielding (2000) treat Photon buildup pretty well. Their coefficients for the Berger...
  32. C

    What are the Limitations of Mumetal for Magnetic Shielding in 3T MRI Systems?

    Hey all, I need to come up with a solution to shield a control box from the magnetic field from a 3T MRI system. With approval (that I will be very persistent to get) I am hoping to be allowed to place the box at around or even outside the 150G fringe surface. Mumetal seems to be the best...
  33. S

    What magnetic shielding should I use?

    I have a circuit board (with chips, resistors, capacitors, etc) that I would like use inside of an MRI magnet (~5 T). Obviously the circuit board itself will cause interference and might not function properly, so I would like to enclose it in a box to prevent any interference. What should I use...
  34. M

    Is covering a high radioactivity alpha source with a low Z material safer?

    Hi all! I have the following question to solve and it's getting me down. Suppose we have an alpha source with very high radioactivity (such as 100kCu) in our workspace. Even though we know that the range of alpha particles in air is about 4 cm and we try to stay away from the source and...
  35. C

    Shielding magnetics to prevent interaction

    Could anybody tell me, if there is anything that can distract magnetic field, but not in the way diamagnetics do. I.E. when I put two magnets on table N|S S|N they will start repulsing themselves, and i want to know, what can i put between them, to avoid reaction of repulsing, so there will be...
  36. E

    EMF Shielding: Examining the Effects on Static Magnetic Fields

    Your opinion to the following will be appreciated Lets imagine a sphere made of a conductor (copper) placed within a static magnetic field. The field will penetrate the within the shier. Next we place inside the sphere a coil producing a variable electromagnetic field. The electromagnetic field...
  37. G

    EMI Shielding Gaskets: Function & Applications

    Hello everyone, Can anybody tell me that, actually what is the main function of EMI shielding gaskets?And i would also like to know the applications of EMI shielding gaskets. Best regards
  38. S

    Magentic induction and shielding

    This happens when the ferro-magnetic material is placed near to the magnet. (call this induced magnetism) BUT if the bar shape ferro-magnetic material's length is compressed into as thin as a sheet of iron, Electromagnetic shielding occurs. -------------------- In the first situation, an...
  39. B

    Shield Principle Clarified: Inside-Outside Electric Field Independency

    Consider an uncharged spherical conductor .It has a cavity carved out of it and there's a charge q in the cavity.Now you get an electric field outside the sphere.All fine.But why does Feynman say that "...no static distribution of charges inside a closed conductor can produce any fields...
  40. S

    Electric Field in Faraday Cage: Effects on Shielding

    i heard that a faraday cage is often used in shielding e.g. sensitive electrical equipment. I was just wondering, because, in http://socrates.berkeley.edu/~fajans/Teaching/cartoons/Shielding/TestChargeShielding_files/frame.htm it seems that the electric field is not zero at ALL times. i.e...
  41. T

    Understanding Magnetic Shielding - Is This Correct?

    I'm struggling to get my head around this concept. As far as I know, magnetic permeability is a measure of the ease at which a magnetic field passes through a body. So if I used a highly magnetic permeable material (steel, aluminium) for a container to shield against external magnetic fields...
  42. T

    Why Are the Results in My PDF Different from the Attached Paper?

    Hi Guyz, Why the results in the paper I've attached aren't like the results I got in my pdf? Please look at the paper in the last line, the second term doesn't correspond to what I calculated, What i calculated is in the pdf file, is it wrong? Why in my work there is exponential terms...
  43. K

    Need info on Ferrite shielding in metallic environment

    Dear all, This is my first post in the forum. I am working on a RFID technology used in door opening systems. The wall readers, we use are typically placed behind the door, as is the case with the metal being used on the front side of the door and in the key hole casings there is the...
  44. M

    About magnetic shielding materials

    Hi all... I was trying to understand the theoretical basis of Magnetic Shielding and I stuck at the point that materials with high permeability concentrate (attract or conduct) the magnetic field, so that the magnetic field lines change its path (redirected) and pass through the material...
  45. M

    Re: Shielding Magnetic Fields of Permanent Magnets

    Hi all, In one of the books I'm reading, it says that shields are only used in the presence of alternating fields. However, in some websites, I see people using magnetic shields for permanent magnets which has a magnetostatic field. I ran some simulations, and the filed of a permanent magnet...
  46. M

    Re: Magnetic Shielding Materials

    Hi all, I was looking into magnetic shielding materials. I have the impression that nickle, copper, steel standalone are good shileding materials. However, some people claim that an alloy of these elements (eg. netics) are better shielding materials. Is this simply an empirical measurement...
  47. M

    Why Are Alloys More Effective for Magnetic Shielding Than Single Elements?

    Hi all, I was looking into magnetic shielding materials. I have the impression that nickle, copper, steel standalone are good shileding materials. However, some people claim that an alloy of these elements (eg. netics) are better shielding materials. Is this simply an empirical...
  48. S

    Shielding at power frequency using femlab

    Hi I am doing shielding at power frequency using femlab. i have done 2D modeling on a room using reinforcement bars instead of a full shield and i wonder why is the bar inclined at 45 degrees will give a better shielding effeciency than at 90 degree? in the real world, when do we use...
  49. H

    Calculating Lead Shielding Thickness for Radioactive Sample Transport

    Hello, i have to do a problem for a written problem set: 1. Shielding. The transport of radioactive samples must follow strict guidelines to ensure that the exposure is very low. A 100 mCi sample of 212Pb is placed at the centre of a cubical lead lined box, each side of which has a length of...
  50. V

    Gamma Rays: Electromagnetic Shielding for Long-Term Protection in Space

    can electromagnetic shielding in space protect humans (for a long period) from gamma radiation?? i:uhh:
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