Magnetic shielding is most effective against steady magnetic fields and low-frequency induction, such as hum.
The concept of radiofrequency (RF) shielding is simple: simply put a barrier between the source of the radiation and the area you want to protect. You can cover over your shielding materials with almost any decorative medium that you like. Starting with the area with the highest field, place the meter in a location which you can find again after shielding is installed.
Complicated shapes and multiple barriers in a vehicle may not permit the placement of shielding in all locations that need it. Keep adding shielding until either you are satisfied with the results, or you find that adding more shielding does not yield any further decrease in readings.
First, let's understand that the magnetic fields from a single conductor wire emanate from that wire in a pattern that could be described as concentric cylinders. Now, understanding that magnetic shielding "works" because it is a better "conductor" of magnetic field lines than air or just about any other material, let's see what happens with 2 different shield designs. In the cross section image at right, we see that the magnetic field lines that would have occurred at the radius of the shield will exist INSIDE the shield. In conclusion, for net current, flat (or nearly flat) shielding is more effective for fields from wiring in the area adjacent to the shield.
The safety or danger of a magnetic field from a powerline depends on more than just the strength of the field. While there are official standards for exposure to electric and magnetic fields, they are based on the amount of field needed to cause immediate harm. Should you fail to get assistance for the power company (likely), you may be tempted to consider shielding. Compared to magnetic field shielding, shielding a home from cell tower radiation is reasonably straightforward. For doors, walls, floors and ceilings, CuPro-Cote or Y-shield conductive paints offer very good shielding and are very convenient. Remember that the attenuation spec for a shielding material is how much radiation penetrates through the shield. In many ways, RF behaves much like visible light, and RF shielding materials behave much like two sided mirrors.
You can use the shield style that goes right onto the phone, or you can line a pocket or purse with a shielding fabric. Conventional speakers incorporate both a permanent magnet and an AC magnetic field to produce sound.
You will have to use magnetic shielding alloys to shield these magnetic fields and you have a choice of several methods. Note:Unlike the bucking magnet method, these shielding methods do not alter the sound quality of the speaker. Because you will be placing the shielding material in close proximity to this strong magnetic field, you will have to take saturation into account. For the layers closest to the magnet, choose a high saturation material such as MagnetShield.
Wrap the MagnetShield around the speaker magnet (notice that it is attracted to the magnet) in a cylinder shape.
If you need maximum field reduction, or cannot open the speaker cabinet, or you simply want to take the easy route, you can simply place flat magnetic shielding alloy between the speaker and the TV.
The magnetic fields at the side of the speaker magnet have different characteristics compared to at the back of the magnet, and different shielding materials are required.
A high saturation material of significant dimensions such as 36"x15" MagnetShield Plate is required here.
Laptops produce at least two types of electromagnetic fields: AC electric fields and AC magnetic fields.
To shield the magnetic fields we recommend that you form a tray under the laptop with Magnetic Shielding Foil if you will have the laptop near you.
If you are using a remote keyboard, you can achieve much higher reduction of magnetic field by making a 5-sided box from Magnetic Shielding Foil. Unlike X-rays, sound, light or bullets, magnetic field lines must travel from the North pole of the source and return to the South pole.
If you are handy, you can use the magnetic shielding materials listed below to make your own hinged shield. GIRON Magnetic Shielding Film, which does not contain Nickel, is unlike any other magnetic shielding material available on the market today. Suitable for small shields on magnets, motors, speakers and appliances such as refrigerators, vacuum cleaners etc.
We have teamed with the design and engineering division of the Giron manufacturer to offer start-to-finish magnetic shielding solutions for residential, commercial, and industrial buildings.
Used for years in industry to shield delicate electronic components from EMFs, this 80% Nickel alloy magnetic shielding foil is now available at affordable prices for home and office use.


The amount of shielding that you will achieve depends on many factors, including the size and shape of the shield. Make sure to check for additional sources of magnetic field (lights, wiring, appliances and so on), that may be located inside adjacent walls, floor, ceiling or within the same room. Click here for a short instructional video on doing a magnetic field survery for shield design.
While the special alloys in Magnetic Shielding Foil, Mag-Stop Plates, Joint Shield, and Metglas, exhibit high magnetic permeability, there are many factors which affect the amount of magnetic shielding you will achieve by using these materials.
Because we have no control over many of these factors, we cannot and do not guarantee any specific shielding performance for a specific application of these materials. Joint-Shield can also be used by itself as an excellent magnetic shielding material when a 4" width and adhesive backing is desirable (wrap it around wiring and conduit, speaker magnets, even small appliances like shavers and hair dryers!). Combining high performance nanocrystalline magnetic shielding alloy sandwiched between layers of clear PET to achieve good performance and easy handling. First line of defense for shielding strong magnetic fields from magnets, speakers, small transformers and motors. Better: One or more layers of MagnetShield (closest to the source of field), followed by one or more layers of a high permeability material such as Joint-Shield or MagStop Plate.
For shielding jobs where you don’t need a high attenuation, this unique material is just the ticket. Attention pacemaker wearers, welders and anyone wanting to shield their upper body from magnetic fields! Magnetic shielding prevents the magnetic field that causes the induction from reaching the low-level circuit. At higher frequencies, it becomes less and less effective because the magnetism takes time to be induced in the material of the shield. Gaps under doors, joints between shield sections, and even pinholes from sewing shielding material can permit these high frequency signals to penetrate. The subfloor can be painted, or a shielding fabric layer can be applied before the final floor surface is installed. It can have very high shielding performance, and in general should be grounded for peak efficiency. As you can see from the image below, the magnetic field lines which intersect the flat shield will be compressed into the shield, leaving less magnetic field on either side of the flat shield. But the magnetic field from a powerline varies from moment to moment depending on how much current is flowing in the wire at the time. Some research has shown that harmonics (higher frequency fields), radio-frequency signals in the line, and power spikes may have more to do with health effects than just the normal 60 Hz magnetic field. The first step should always be to record readings of the magnetic field strength over a period of a few days using a reliable AC Gaussmeter to find out if you truly have a problem. But because shielding materials are conductive, be very careful to avoid allowing them to come into contact with electric wires to avoid a shock hazard. Keep in mind that with magnetic fields, you can either shield the source of the offending field, or shield the thing(s) that you wish to protect. There, you will find a donut shaped magnet, proportional in size to the size of the speaker, over which you will place a cup shaped shield. The material is thick enough to provide good shielding, but still can be cut with a scissors and shaped by hand. Unlike the way a lead shield stops X-rays, magnetic shielding materials create an area of lower magnetic field in their vicinity by attracting the magnetic field lines to themselves.
Strong magnetic field emissions (depending on how much electric current is flowing) and electric field emissions can make the nearby area hazardous to occupy, especially for long periods.
Suitable for high field strength applications requiring high saturation and good permeability, it is both thin and strong, and unlike Mu-metal™ it is very tolerant to bending or shaping without losing its shielding properties.
The 30" wide "fully hydrogen annealed" plates offer the best shielding available (up to 10 times the shielding effectiveness of stress-annealed alloy) and should not be soldered, welded, or heated in any way. The list of such factors includes: size and shape of the source of the magnetic field, size and shape of the shielded area, seams in the shielding material, frequency of the magnetic field, distance from shield to source, orientation of shield to the source, thickness and heat treatment of shielding material, etc.
This occurs when the Earth's magnetic field (about 400 mG) interacts with a large shield, reducing its effectiveness, unless special "high saturation" (MagnetShield) shielding alloys are incorporated into the design. Very light weight and flexible, easily trimmed with scissors this material will provide good high frequency magnetic shielding for moderate to low intensity fields below 1000 kHz. Strong magnetic fields are harder to shield because they tend to "saturate" the shielding material. If you want to shield 2 adjacent magnets from eachother, each magnet should have its own shield.
The faster the inducing magnetic field fluctuates, the less effective the shield is in conveying the magnetic field around the shielded circuit. If the floor in already installed, you can lay shielding fabric, and cover it by a large area rug or sheet linoleum. It is important that the meter position be repeated in exactly the same position (before and after shielding), as changing the meter position will change the readings.


The AC magnetic field is only present when the speaker is activated, and varies in frequency and strength with the pitch and volume of the sound produced. Note that attenuation will be greatest close to the speaker magnet, where the field is strongest (most interfering) anyway. A good, inexpensive way to check for shield performance and the best position for the shield is to use a Pocket Magnetometer.
Note: There will be a position somewhere between the back of the speaker magnet and the front of the TV which will yield "near perfect" shielding. Covering the keyboard area of the laptop with a shielding fabric such as High Performance Silver Mesh will reduce electric fields from these areas while still allowing you to see the keyboard.
But if a material with a higher permeability is nearby, the magnetic field lines, efficient creatures that they are, will travel the path of least resistance (through the higher permeability material), leaving less magnetic field in the surrounding air. Shielding is certainly possible, but the shield must not hamper quick and easy access to the controls inside the box. It’s a picture (or poster) in a nice frame, with high performance Giron shielding material behind the picture.
This is a generous .010" thick, fully hydrogen annealed magnetic shielding alloy with adhesive backing (rated 0 - 200°F) on one side. This 4" wide foil is a hefty .010" thick and has an exceptionally high magnetic saturation of 21400 Gauss and maximum permeability of 4000. High saturation and moderate permeability make this ideal for shielding weak magnets, or stronger magnets with many layers of shielding. You can paint over the shielding paint with any color of latex paint to achieve any appearance you like.
Every vehicle will have multiple sources of magnetic field, some of which may be in areas that are difficult to access for shielding. Notice also, that the magnetic field lines are more concentrated near the wire, and less concentrated as the distance to the wire increases.
One rule of thumb that is used by some experts is that you should limit your exposure to 60 Hz magnetic fields which are in excess of 2.5 mG.
The magnetic field from the two sources can deflect the electron beam in a cathode ray tube monitor (TV) causing distortion of the image, sometimes called jitter (and possible damage to the equipment). Move either towards the speaker or towards the TV from this point and you will loose shielding effectiveness. Magnetic field reduction is 30 to 60% up close to the surface, depending on wire configuration. Can be formed into magnetic barriers on cellular phones, microwave ovens, doorbell transformers, VDTs, buried wiring, and more.
Just right when you need to cut magnetic shielding materials including Giron, MagnetShield , and Magnetic Shielding Foil.
This material is particularly suited for achieving precise levels of partial shielding as you can add exactly the right number of layers to achieve the desired result.
This reduces the induction inside the shield by a factor dependent upon the permeability of the magnetic material of which the shield is made, the thickness of this material that provides a magnetic conducting path, and the frequency of the magnetic fluctuation. You could also use a shielding fabric such as Nickel Copper RipStop or AL60 behind the wall. Use screws, pop rivets, tape, glue or any other mechanism you can think of to keep the shielding material in place.
To achieve a reasonable degree of shielding, you would have to create a metal vault around your house, using thick metal plates with no windows. Therefore be sure to check the position with a Pocket Magnetometer or digital DC Gaussmeter. With snug fitting shapes, get as much as 75% attenuation of the magnetic field with one thickness. This method offers much less bulk and better appearance than the old overlap technique and provides excellent shielding integrity.
Naturally, some situations may require shielding of both the back and the sides of the speaker cabinet.
In our tests, a 2-foot section of Giron in a 24x36 inch frame provided 50-70% reduction of magnetic field.
Works with AC or DC magnetic fields (0-1000 Hz), and will tolerate temperatures from 32° to 122°F. If your largest piece of shielding is not wide enough, you can place pieces next to each other, with 1-2 inches of overlap where they meet. Placing magnetic shielding material around your body is possible, but again not very practical.



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