trying to buy quality EM meter and need help
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Hi all!
Just joined because I became interested in this topic when power company decided to build a 2x110kV power line near my house. I would like to approach this problem rationally with measuring tools to determine how far the EM field can reach before it becomes indistinguishable form other present radiation. Upon reading more about it I also became more aware of other source, especially HF ones inside my home and cell towers. I began to search for a viable measuring tool and quickly realized that I'll need to buy several to cover different frequencies and radiation magnitudes. If I may, I would like to ask everyone here a few questions: 1. Why do experts recommend measuring RF with a single meter while low frequency radiation is measuring magnetic radiation separated from electrical field? 2. Am I required to re-certify or re-calibrate my meters every once in a while to assure that the accuracy is still decent? I am afraid that this might prove to be very costly, especially in my country. 3. Some recommend using body volt meter to measure the electric potential on the body itself? How does it compare with mid tier hand-held meters and how would one compare the measurements from both methods? 4. I noticed that pricier gauss meters measure magnetic field in all 3 axis, 3d basically. But I couldn't find one that does the same with electrical field. Why is it so and do I even need to measure it in 3d? If I measure in 1 axis, do I need to take 3 measurements and combine them? 5. What exactly does noise represents on the measurement screen (I noticed HF meters often include signal amplifier but not LF ones)? I did email all of these questions to 2 re-sellers and 1 manufacturer and haven't received any replies in days even thou the meters in question were $500-$1000. I hope I can find some answers on this forum:) Thank you all for your effort and time. |
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This post was updated on .
1) RF radiation is a combination of magnetic and electric fields twisting around each other in a "wave". AM=magnetic receiver, FM=electric receiver, but the actual signal is electromagnetic (both E and M). Electrons flowing through the high voltage lines generate both E and M.. and any other small wires with currents being carried. You just have to understand RF is really EM and receivers for high RF, like the meters you see online, are E based because that's easier to process. It makes sense to measure M in the low frequencies because that's where it exists the most, a 2.4ghz signal has a very tiny M component. I don't know what increases the E field though, it's likely voltage and amperage. 2) Not really, not with cheap meters. 3) That will show you if there are big problems.. You can find youtube videos how to do it. Likely the wires in your home will influence the readings more than the power lines outside your home. 4) E fields are "everywhere", no axis needed. (Edit: This is what it seems like when measuring close to a power wire which is emitting E fields, however, at further distances, E fields will have to have the antenna aimed in a certain direction to pick it up, so it does seem like it has an axis after all, and theoretically it should. So a cheap RF meter will have to be waved around to pick up the field, or you might miss it. But, you can generate E fields even with statically charged clothes, .. so it's a bit odd how they work. ) 5) Haven't seen that.. To answer your concern...Likely 200 to 500meters is the distance, depending on weather and humidity. Will this impact you? Maybe, maybe not.. If you really want to measure, buy a ME meter from Gigahertz , like ME3030B, or better in their ME series, if you can afford. Those are best for ME measurements. You may find your own home radiates more than what comes from outside.. or the other way around, which I'd be surprised. You'd have to live really close, like 50-100 meters close, to be measuring it inside your home. With RF measurements are very unreliable, but with E/M, since the frequency is quite constant and low, it's easier to measure. E fields still require ground to measure, but not M fields. Will that tell you everything though, likely not... E/M being low is not everything. Power lines can contain dirty electricity in other frequencies which will radiate out as well, .. so there's a whole bunch of E/M frequencies that are being broadcast , and the line is just a huge antenna... So you can think you're safe, and your E/M meter doesn't show much, but if you had other instruments you'd be picking up more things. They'd be tiny, but they could still cause issues. EHS people can have problems from extremely low strength fields that can barely be measured.. It's not like you measure a huge signal and that's the only place you may have a problem.. likely that's how it starts, with a huge exposure, but once you become sensitive, then the meters can show very low readings and that may still not be a good place to be. It's good you're trying to measure it, hopefully the ME meter will give you something to go on. |
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In reply to this post by miran80
I am happy to provide some answers:
1. Why do
experts recommend measuring RF with a single meter while low frequency radiation
is measuring magnetic radiation separated from electrical field?
At lower frequencies, the electric and magnetic fields act independently. You cannot know anything about one if you only measure the other. You need different types of sensors to measure them, hence different meters. At higher frequencies (RF frequencies) the electric and magnetic field are coupled. So if you measure one, you can calculate the other. It is much easier to measure the electric field, so that is what most RF meters do. 2. Am I required to re-certify or re-calibrate my meters every once in a while to assure that the accuracy is still decent? I am afraid that this might prove to be very costly, especially in my country. Most consumer-grade meters cannot be re-calibrated. Unless you are doing legal work or scientific research, a calibrated instrument is not needed. After all, you mainly want to know if the levels are high or not, what type of radiation you have, and where/what is the source. A mid or low end instrument does all that just fine. 3. Some recommend using body volt meter to measure the electric potential on the body itself? How does it compare with mid tier hand-held meters and how would one compare the measurements from both methods? Electric fields will induce a body voltage in the body. However, because of position, grounding, ground currents and other factors, you cannot know anything about the electric field just by measuring body voltage. And you can't know anything about body voltage by measuring electric field alone. 4. I noticed that pricier gauss meters measure magnetic field in all 3 axis, 3d basically. But I couldn't find one that does the same with electrical field. Why is it so and do I even need to measure it in 3d? If I measure in 1 axis, do I need to take 3 measurements and combine them? It is quite difficult to make an electric field meter in 3 axis. Yes, you should rotate the meter in all directions to get a better idea of the total picture. Besides, it is often the case that there are multiple sources (overhead lights, wiring in the wall, a ceiling fan on the floor below, etc) that make searching in all directions imperative. 5. What exactly does noise represents on the measurement screen (I noticed HF meters often include signal amplifier but not LF ones)? No
sure what you are asking here. If you want to clarify, I will be happy to
answer.
Best regards,
From: miran80 [via ES] [mailto:[hidden email]] Sent: Friday, November 09, 2018 8:49 PM To: emil Subject: [ES] trying to buy quality EM meter and need help Just joined because I became interested in this topic when power company decided to build a 2x110kV power line near my house. I would like to approach this problem rationally with measuring tools to determine how far the EM field can reach before it becomes indistinguishable form other present radiation. Upon reading more about it I also became more aware of other source, especially HF ones inside my home and cell towers. I began to search for a viable measuring tool and quickly realized that I'll need to buy several to cover different frequencies and radiation magnitudes. If I may, I would like to ask everyone here a few questions: 1. Why do experts recommend measuring RF with a single meter while low frequency radiation is measuring magnetic radiation separated from electrical field? 2. Am I required to re-certify or re-calibrate my meters every once in a while to assure that the accuracy is still decent? I am afraid that this might prove to be very costly, especially in my country. 3. Some recommend using body volt meter to measure the electric potential on the body itself? How does it compare with mid tier hand-held meters and how would one compare the measurements from both methods? 4. I noticed that pricier gauss meters measure magnetic field in all 3 axis, 3d basically. But I couldn't find one that does the same with electrical field. Why is it so and do I even need to measure it in 3d? If I measure in 1 axis, do I need to take 3 measurements and combine them? 5. What exactly does noise represents on the measurement screen (I noticed HF meters often include signal amplifier but not LF ones)? I did email all of these questions to 2 re-sellers and 1 manufacturer and haven't received any replies in days even thou the meters in question were $500-$1000. I hope I can find some answers on this forum:) Thank you all for your effort and time. If you reply to this email, your message will be
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