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Cell phone shields
Magnetic Shielding
Computer Shields
Stetzer Filters
Faraday Canopies
Smart Meter shields

How To Test Cell Phone Shielding Products

Cell phone, mobile phones, and cordless phones produce both magnetic fields and radiowaves (microwaves). Most cell phone shielding devices are designed to reduce the radiowaves. But you can test for either, if you wish.

The tricky part about measuring the radiation from a cell phone is that the emission strength varies widely over time. There will be strong bursts of varying intensity, followed by quiet periods. This makes it hard to compare "apples to apples". Also, because you are measuring up close to the source, you must use a near field meter AND you must maintain the postion of the meter very precislely.

First, you must have a proper meter. To check for magnetic field emissions, an AC Gaussmeter will work. Most AC gaussmeters will have an internal probe. Simply position the gaussmeter on the phone. Note carefully where the meter is positioned. Make a call and watch the readings. Notice the highest and lowest readings, and make a mental note of the "average" reading. Now, insert the magnetic shield, and repeat.

Cellphone Shielding Cellphone Shielding Cellphone Shielding To check for radiowave emissions, use an RF meter with Near Field antenna. Again, position the antenna loop on the phone (becasue the entire antenna stem has some sensitivity, it is best to postion the entire antenna over the area that will be shielded). Note carefully where the loop is positioned. Make a call and watch the readings. Notice the highest and lowest readings, and make a mental note of the "average" reading. Now, insert the shield, and repeat.

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How To Test Shielding Fabrics

Shielding fabrics can accomplish 3 things: shield radiowaves, shield electric field, grounding. Each requires a different test set-up.

Fabric Shielding Fabric Shielding

Testing RF Shielding
First, you will need a suitable RF meter. It also helps to have an RF source which produces a steady emission (such as a key fob, or radiowave remote control). Using background levels can be tricky if the levels vary widely. Position the RF source and the meter so that both will remain absolutely still. Start by measuring the ambient background level to see if it varies widely. Now, activate the RF source and read the level on the meter. Finally, wrap the antenna of the RF meter in the shielding fabric. Re-activate the RF source and make the measurement. Grounding the fabric may improve shielding performance.

Testing Electric Field Shielding
Using your electric field meter, identify a source of electric field, such as a lamp cord which is easy to reach. As aways, set up the source of the field and the meter so that they remain in exactly the same position. Make a reading. Now insert the fabric between the source and the meter. The fabric MUST be grounded. Take the final reading.

Testing Grounding
Here, you will need a way to meaure how well your body is grounded. The Body Voltage Meter is perfect for this purpose. Locate a source of electric field, such as a lamp cord. Set up the Body Voltage Meter and the grouded fabric nearby. Now, place a part of your body near the lamp cord (such as one foot), and another part (maybe the other bare foot) near the grounded fabric. Hold the meter handle and measure your body voltage. Now touch the grounding fabric with your bare skin and re-measure. You should see a large decrease.

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How To Test Shielding Clothing

Clothing Shielding Clothing Shielding

Shielded clothing will reduce your exposure to radiowaves. Their effectiveness is easy to test with an RF meter. It also helps to have an RF source which produces a steady emission (such as a key fob, or radiowave remote control). Using background levels can be tricky if the levels vary widely.

First, put on the shielded garment. With the RF source, activated, make a measurement just outside the garment. Now position the antenna of the meter inside the garment and repeat the measurement. Try to plan ahead, so that the meter does not change position while you place the garment over it.

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Magnetic Shielding Magnetic Shielding

How To Test Magnetic Shielding

There are many ways to do this test. Here is perhaps the simplest:

Using a long extension cord laid straight out on the floor, plug in a high current device such as a hair dryer. The hair dryer must be at a good distance from the place where the test will occur. Place your AC Gaussmeter directly on the wire. First measure with the hair dryer off (Is there a lot of background field? If so, do the test in a different location.) Now, turn on the hair dryer and note the gaussmeter reading. Finally, slip the magnetic shield between the meter and the cord and see the difference in the meter reading.

Remember: this is a test of the shielding performance of the material itself. The size, shape, and position of the shield in your application will all affect total shield performance.

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Stetzer Filter

How To Test Computer Shielding

The HARApad is very easy to test. You will need a gaussmeter and a laptop computer. Make a "bridge" with 2 piles of books which is tall enough to span your gaussmeter. Place the laptop on the bridge. Turn on the laoptop and make a measurement of the magnetic field with your gaussmeter. Note that the strength of the field varies with position. Now, without moving the meter, slip the HARApad into position and repeat the measurement.

Signal Tamer Router Guard

WaveCage and Signal Tamer are tested using an RF meter. First, set up the RF meter in a fixed position. Unplug the wi-fi router and measure the background levels of radiation with your RF meter (if there are other RF sources nearby, such as cell phones, cordless phones, iPads etc., move them away). Next, turn on the wi-fi router and measure its radiation output. Finally, put the wi-fi router inside the shield, and re-measure.

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Stetzer Filter Stetzer Filter

How To Test Stetzer Filters

Remember that Stetzer filters reduce "dirty electricity", not the 50/60 Hz electric and magnetic field emitted from wires and appliances. So you can't use a standard electric or magnetic field meter to check performance. Instead, use the Stetzer Microsurge Meter. Find an outlet where nothing is plugged in. Plug the meter into one of the openings and notice the reading. (allow a moment for the meter reading to staibilize). Last, plug a filter into the other opening in the outlet and watch the meter reading go down.

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Shielding Paint

How To Test Shielding Paint

Shielding paint will reduce radiowave signals. One-sided shields can be tricky, not because the signal comes through the shield, but because it can come around the shield. To eliminate this, you can create a shielded enclosure. First, you need an RF meter. Next find a cardboard box and paint the entire surface, either inside or outside, and allow it to dry. Now, make a measurement outside of the box. Next put the meter inside the box (with a small flashlight if necessary). Look through a small hole in the box to read the meter. The levels will be greatly reduced.

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Faraday Canopy Faraday Canopy

How To Test Faraday Canopies

Canopies will shield radiowaves, so you need an RF meter and a steady RF source such as a key fob. Note: please don't call us asking why your cell phone or laptop bars don't change*. This is not a valid way to test for shielding performance. Set up the canopy, and set the RF source in a fixed position outside the canopy. Make a measurement with the RF meter outside the canopy. Now, put the meter inside the canopy and repeat the measurement.

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How To Test Smart Meter Shields

Smart Meters produce a mix of emissions. Most people think of microwave (radiowave) emissions. But there will also be magnetic fields, electric fields, and dirty electricity produced by the Smart Utility Meter. Smart Meter shields address the radiowaves.

You will need a special kind of RF meter for this job because the emitted signal from the Smart Meter is a very short, very fast burst. The detector needs a fast reaction time to pick up the signal reliably. The Acoustimeter and the High Frequency Meter are both well suited for this purpose.

Set your detector in a fixed position near the Smart Meter. Make measurments over a few minutes, looking for the highest readings you get during the bursts. Without moving the detector, apply the shield, and repeat your measurments.

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* Cell phones and laptops can operate on a very small fraction (1/millionth to 1/billionth) of a strong signal. You know this is true because you can be miles away from a cell tower and still get reception. At this distance the signal from the tower is very weak. Shielding material may reduce the signal by 99% or more. But this means that 1% (or less) of the signal still comes through. 1% of a strong signal is plenty for the device to still operate, and won't even reduce 1 bar. But 99% reduction is still way better than no reduction!

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