Because magnetic fields are oriented in space, a sensor will only detect the field properly if it is aligned with the field. A single axis meter has only one sensor in it. Therefore to get a correct reading with this type of meter, you must slowly rotate the meter until you find the maximum reading. This will be the correct reading. If the meter is turned 90° from the maximum reading, it will read nearly zero. It is easy to understand how it is possible to get a lower than actual reading if the meter is not properly aligned.
A three axis meter has 3 sensors in it, all aligned at right angles to each other. Therefore, this type of meter is always correctly aligned and no rotation is required to get a correct reading. This type of meter takes less time to use but generally costs more that its single axis counterpart. See 3-Axis Digital Gaussmeter and Trifield Meter for examples of 3-axis gaussmeters.
Whether is it electric fields, magnetic fields, or radiowaves, the source of the field will always be in the direction of the strongest signal. It is critically important to avoid being fooled by thinking that the meter points in the direction of the source.
A perfect example of this phenomenon involves powerlines. You should remember that the direction of magnetic field lines around a current carrying wire is circularly perpendicular to the wire. So alongside the wire, the field lines are vertical, while underneath the wire, the field lines are horizontal. The proper orientation of a single axis meter may point the meter at the wire, or straight up and down, or even horizontal, depending on the orientation of the sensor in the meter and the position of the meter relative to the wire. Furthermore, the orientation of a 3-axis meter is irrelevant to the reading, so it could be pointing in virtually any direction and still give a correct reading.
Only by moving the meter bodily toward, then away, from a suspected source can one determine the location of the source.
There is much concern about the health effects resulting from microwave radiation from cell tower and radio antennas. Biological effects have been clearly established at levels well below the government exposure limits.
However, people are often surprised to learn that the strength of the signal from a cell tower or radio antenna is extremely small if you are any distance at all from the antenna. At 100 yards, the signal strength is well below the sensitivity of most meters. In order to measure these signals, you need an extremely sensitive meter. You also need a meter which can accurately process a digital signal (which is different from an analog signal in the way it interacts with a meter), and it would be useful to have a meter which is directional, so that you can take a measurement of a specific tower, without interference from extraneous sources behind or to the side of you.
For these reasons, there is only one best meter we recommend for measuring antenna: HIGH FREQUENCY METER. It has the sensitivity (10 picoWatts/cm²) to measure an antenna miles away, process analog or digital signals correctly, and it'S antenna is directional.
Of the low cost meters, the MicroAlert may be useful in some circumstances. This device is somewhat directional and it is somewhat more sensitive than the other low cost RF meters (1 microwatts/cm²). Note that is not a true meter, but rather an alarm to alert you when you are exposed to radiation above the threshold of the meter (somewhat similar to a radar detector in your car). Even so, it can be useful for determining if you are in a microwave hot spot and if your shielding methods are effective.
The 3-axis RF Meter is probably the best pick for non-technical users. It is very easy to use, very sensitive ( down to 0.4 nanoWatt/cm²) and gives a calibrated, digital readout of field strength.
This is perhaps the trickiest measurement you are likely to attempt. The reasons include:
There are NEAR FIELD probes which can be connected to a spectrum analyzer for a cost of $30,000 or more. And of course, there are $100,000 SAR machines for doing SAR testing. But what can an ordinary person use to measure the output from his phone or check the effectiveness of a shield?
We recommend the ScanProbe. For about $300, you can use this NEAR FIELD meter to check all surfaces of your phone and establish where the hot spots are. The ScanProbe-C can be attached to an oscilloscope or DMM to get even more precise information about the strength of the field.
When measuring distance, you can use a variety of units: inches, centimeters, miles, fathoms, etc. Some units are larger than others. Some are more familiar than others. However, regardless of the units you use, the distance you measured remains constant but the number you get can vary widely.
Similarly, when measuring radiofrequency signal strength, many different units can be used. They are all equally valid*, and you can convert from one unit to another. But some units are much bigger than others.
You wouldn't measure the distance from Paris to Rome in inches; you would use a bigger unit... perhaps kilometers. Likewise, you would use a very small unit to measure the thickness of a human hair. So, when measuring the generally low levels of background RF radiation, you can use a small unit, such as V/m. When measuring the relatively large amount of radiation that leaks from a microwave oven, you can use a larger unit, such as mW/cm2.
The image shows the relative size of some units compared to 1 V/m. Notice that A/m is a much larger unit, almost 400 times the size of one V/m. A/m is better suited for measuring very strong radiation.
* Engineers will have a preference for one unit over another, particularly when measuring in the near field.
There are 3 main categories of meter that are popular among paranormal researchers:
AC Gaussmeters: The hands down favorite is the 3-axis Trifield Meter . With its fast reaction needle gauge and 2 sensitivity scales, this meter is so easy to use right out of the box. Other choices include the 3-Axis AC Gaussmeter for high accuracy, the Single Axis AC Gauss Meter for economy, and among the low cost single axis meters: GaussMaster offers an audio tone, and E.L.F. Zone offers lights which are very useful in the dark.
Remote Temperature Scanner: The easiest way to check for cold spots is the Remote IR Thermometer. Complete with a laser pointer for good aim, simply point and shoot to get instant temperature readings of surfaces 10, 20 or 50 or more feet away.
Exotic Meters: Some researchers believe that paranormal activity can ionize the air. This phenomena is easy to measure with the Air Ion Counter. Radioactivity can be affordably checked with the Monitor 4. Changes in DC electric and magnetic fields can be picked up with the Natural EM Meter, which also offers an audio tone for low light conditions. A motion detector can be used to remotely detect moving objects, opening doors and windows, and the appearance of hot spots.
A great book on ghost hunting tools and techniques is Ultimate Ghost Tech by Vince Wilson.
This is a very tough question to answer. Harassment could take many forms: chemicals, ions, sound, microwaves (what frequency?), light, covert technologies, and so on. There is no one meter that can measure all these different phenomena. Furthermore, your symptoms may be due to something else altogether such as allergies, migraines, high blood pressure, or a thousand other conditions.
If you are serious about determining if you are being intentionally exposed to electromagnetic fields, then the logical place to start is with meters which offer the widest range of sensitivity.
One low cost possibility is the combination of the Trifield Extended Range Broadband Meter plus the Natural EM Meter will cover the whole range from DC to 2.5 GHz. This combination offers the ability to distinguish if the offending field is AC or DC, and whether it is electric, magnetic or microwave.
All meters have a range of exactly zero feet. This means that all gaussmeters, electric field meters, RF/microwave meters, etc. can only measure the strength of the field AT THE LOCATION OF THE METER.
What distinguishes one meter from another is the sensitivity. In other words, what is the smallest field strength that the meter can detect? A gaussmeter with a sensitivity of 0.1 mG is more sensitive than a meter which can only detect down to 1.3 mG. While the meter which is more sensitive can be successfully used further away from the source of the field, it is still only measuring the field at the location of the meter.
So the next question is: if you have a meter with a certain sensitivity, how far from a source of field is it useful? The answer to that depends on 3 factors:
Without knowing a great deal about the nature of the source, it is impossible to determine at what distance a given meter will begin to detect its field. What you can do is easily compare the minimum sensitivity of one meter to another. This specification is given in the description of most meters.
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