EMR Monitoring Tools
In our modern world, we are increasingly immersed in energies from man-made devices. The fact that they transpire within an invisible portion of the elctromagnetic spectrum, does not mean they have little or no effect.
For consideration of suitability, we can divide these into three groups of frequencies, specified in "Hertz" (Hz) or cycles per second. Low frequency which arises primarily from mains radiation from wiring and appliances. Radio frequency as emitted by wireless technologies such as mobile phones, radio, and routers. Finally the specialised bandwidth surrounding 2.1GHz dedicated to Wi-Fi networks.
Below are a few cost-effective instruments and software applications for monitoring each of these bands in turn. They also provide the capability to estimate the efficacy of any user-instigated countermeasures. There is a wide range of similar products available. Inclusion herein is representative does not constitute an endorsement for any given purpose. See our April 2015 Newsletter for how to interpret measurements.
Please note, these options are for informal measurements only. For an reliable "EMR survey", contact a trained professional with certified in-calibration equipment.
Tenmars ELF Magnetic Field Meter - TM 191
A good general purpose meter for low frequencies, 30-300Hz, priced at around $75. They are manufactured in China, and available at numerous outlets, including eBay and Amazon.
Cornet Electrosmog RF Meter - ED85EXS
Within its affordable $220 price-point and detailed LCD display, this is perhaps the most highly regarded personal for RF, 1MHz-8Ghz. Also available at the outlets mentioned above.
Cornet Meters. http://www.cornetmicro.com/
Gigahertz Solutions - Kit
The German-made gaussmeter and RF meter below are available separately, but can also be purchased as a kit with carry case for around $600. The latter has the advantage of a log periodic antennae that enables directional field intensity readings.
This type of meter, known as a "spectrum analyser" not only indicates signal strength but also provides a visual indication of the exact frequencies (signal sources) presently active within any given bandwidth. It is packaged with software, similar to Airview below, but covers the entire RF range. Normally, this capability would require a lab grade instrument costing $10,000 or more. RF Explorer, is priced in Australia at around $325 from the supplier below.
Low Cost Shielding
If your meter does not have a directional antenna, how do you determine where the strongest signal is coming from? For example, this is particularly relevant for knowing which side of a room to install shielding to reflect incoming microwaves.
The cheapest shielding material is aluminised mylar, in the form of emergency blankets that can be purchased at camping/disposal stores, or on auction websites for a few dollars each. Hold the RF meter in one hand with the display facing you. Behind this, unfold a large piece of the reflective material. Now slowly rotate your body, and these items, 360 degrees while looking for the highest reading. When this occurs, the dominant incoming signal(s) are behind you, and it is one that wall that shielding material can be applied.
If there is no substantial drop in reading, it means multiple signals are coming from different directions. This is a complex scenario that requires more elaborate solutions.
Be aware that microwaves are described as "quasi-optical", meaning that while directional, they can reconverge within a certain distance beyond the edges of any shielding surface. Hence, for successful shielding, it is necessary to confirm an actual reduction in field strength with a meter.
Note that the principle above relies upon the propensity of RF to be easily reflected. 50/60Hz mains radiation cannot be similarly shielded.
The following free programs will work on most any PC that has a built-in wireless modem. They are intended to help locate available networks, as well as assist service people optimize Wi-Fi setups, and detect possible interferrence from other networks in any given locality. The software is equally useful for concerned citizens wanting a graphical representaion of how many 2.4GHz signals are currently affecting them, as well as their relative activity and field strengths. Note that these tools are only designed to detect Wi-Fi.
inSSIDer Home. http://www.metageek.net/products/inssider/
This is the "little brother" of Ekahau Site Surveyor, and is offered as a free download upon registration. Its function differs from the foregoing applications, and works in conjuction with your laptop's Wi-Fi modem. You load a map of a building or neighbourhood into the program. This then appears on your computer screen. As you walk around, you stop at any desired location, put the mouse poiter on the corresponding position on the map, and click the trackpad. This creates a measurement point of Wi-Fi signal levels at that spot. After you do this numerous times over a given area, the software then generates a colour-coded map (green strongest) indicating the gradient of field intensities within it, as well as the number and identity of signal sources. The result to the left was obtained by walking around one block in cnetral Byron Bay.
Ekahau Heatmapper. http://www.ekahau.com/wifidesign/ekahau-heatmapper#!overview-0
The system below, from Ubiquiti, is probably the cheapest option for persons wishing to view or analyse the actual Wi-Fi spectrum in real time. The package includes a dedicated USB dongle. Sells for $39 in the US, and around $95 in Australia.
AirView2 EXT. http://www.ubnt.com/airview