Battery Junction - Olight
Page 1 of 2 12 LastLast
Results 1 to 30 of 35

Thread: How do I detect and measure RF/EM radiation?

  1. #1
    Flashaholic* LowBat's Avatar
    Join Date
    Jan 2005
    Location
    San Jose, CA
    Posts
    2,524

    Question How do I detect and measure RF/EM radiation?

    I maybe moving next to a rather large communications tower. I'm wondering what sort of radiation sould I be concerned about and how do I measure it? I'm guessing radio frequency energy and perhaps electro-magnetic radiation are what I need to be looking for. As I know very little about this stuff, I thought I'd see if we had some expects on board who could enlighten me. I'm also guessing a geiger counter isn't the right measuring device for this type of radiation.

  2. #2
    Flashaholic* carbine15's Avatar
    Join Date
    Nov 2005
    Location
    Slaughter, WA
    Posts
    1,986

    Default Re: How do I detect and measure RF/EM radiation?



  3. #3
    Flashaholic* London Lad's Avatar
    Join Date
    Feb 2006
    Location
    Suffolk U.K.
    Posts
    1,751

    Default Re: How do I detect and measure RF/EM radiation?

    Might be cheaper to move !


  4. #4
    Flashaholic* LowBat's Avatar
    Join Date
    Jan 2005
    Location
    San Jose, CA
    Posts
    2,524

    Default Re: How do I detect and measure RF/EM radiation?

    That looks expensive and complicated. I'd venture to say the manual would probably resemble a phone book. Anything a little simpler for a novice like myself?

  5. #5
    Flashaholic* Lasernerd's Avatar
    Join Date
    Dec 2002
    Location
    The Great Pacific Northwest,home of the Goonies,Short Circuit
    Posts
    709

    Default Re: How do I detect and measure RF/EM radiation?

    AM radio hooked to Spectrum labs software
    http://oathkeepers.org/oath/join/
    Which LEO' here agree with this??

  6. #6
    Flashaholic* Steve K's Avatar
    Join Date
    Jun 2002
    Location
    Peoria, IL
    Posts
    1,985

    Default Re: How do I detect and measure RF/EM radiation?

    It depends on what sort of concerns you have.

    If you are worried about violations of FCC regulations, just verify that your radio, TV, cell phone, cordless phone, etc. still work okay. If there's no degradation in their performance, then you are fine.

    If you are worried about health issues, then I'm not sure what to tell you. Are there any standards? I'm betting that there are some standards regarding how much RF a microwave oven can emit, and I think there are some affordable instruments to measure this emission. Other than this, you may be left with more empirical sorts of experiments. For instance, if you can take a hot dog out of the fridge, set it on a plate on the counter, and it cooks just sitting there, then you probably have a problem with microwave emissions. :-)

    Those are all of the low-cost options that I can think of. The proper way to measure RF levels is indeed to use a spectrum analyzer, and that's not cheap. There are places that rent this sort of equipment, if you are interested. And then there's the question of what level of RF is acceptable. I know the specs for the industry that I work in, but I'm sure that the requirements for (intentional) broadcasting is different.

    good luck,
    Steve K

  7. #7

    Default Re: How do I detect and measure RF/EM radiation?

    Hi Lobat Go to www.trifield.com and check out the "trifield meter". At $ 145.00 these work very well and have been around for years. Not a Lab Standard but will do what you want quite well.

  8. #8
    Flashaholic* carbine15's Avatar
    Join Date
    Nov 2005
    Location
    Slaughter, WA
    Posts
    1,986

    Default Re: How do I detect and measure RF/EM radiation?

    i read of some studies that showed a correlation between increased beta radiation and healthier offspring, longer lives and fewer diseases. If there's no annoying buzzing sound you should be fine. That buzzing sound is your brain frying, plus it's really annoying.
    Last edited by carbine15; 12-06-2006 at 03:53 PM.


  9. #9
    Flashaholic* LowBat's Avatar
    Join Date
    Jan 2005
    Location
    San Jose, CA
    Posts
    2,524

    Default Re: How do I detect and measure RF/EM radiation?

    I just want to get a general idea of exposure levels. It sounds like that trifield meter is about what I'm looking for.

    Thanks everyone!

  10. #10
    Flashaholic*
    Join Date
    Apr 2001
    Location
    Massachusetts
    Posts
    4,852

    Default Re: How do I detect and measure RF/EM radiation?

    We have to do EMI testing in our products. The product is fired up and a directional antenna is pointed at the object from a set distance. The antenna is attached to a spectrum analyzer where a spectrum sweep is performed. We always pick up a couple of local strong radio stations but they are ruled out because we do an ambient reading first with the unit under test not operating and then subtract the ambient reading when testing with the device on. Let me tell you, it can be a pain in a butt to find and seal the emi leaks in some of the devices.

    Not sure of a home EMI cost effective testing solution.
    I live in a van down by the river

  11. #11

    Default Re: How do I detect and measure RF/EM radiation?

    Geepondy,
    There's an old saying amongst those of us that have to take prototypes and make them EMC compliant, "Ambients are my friend." More than once I've blazed through a certification test because of the ambients "hiding" a few problem frequencies.

    LowBat,
    For the most part RF energy decays as a square root of the distance that you are away from the transmitter (this holds mostly true for unidirectional xmtrs, I believe.) Meaning, if you're 10ft away from the transmitter, then move to 20ft away (a doubling of the distance) the power falls off by the inverse of the square root of the distance you moved away, or 1/sqrt(10). You can see that it doesn't take too long to get really small numbers.
    You're subjected to MUCH greater levels of RF by putting a cell phone right next to your brain!


    Ordin
    ...Everything I know about the light at the end of the tunnel I learned from Wiley E. Coyote...

  12. #12
    Flashaholic* hopkins's Avatar
    Join Date
    Nov 2007
    Location
    California
    Posts
    906

    Default Re: How do I detect and measure RF/EM radiation?

    A simple way to detect RF is with an AM radio. Walk around your home with
    a portable AM radio, turned up loud and hold it near your computer monitor,
    television, fluorescent lights, electric bed blankets, microwave ovens,
    cell phone LCD displays, digital wrist watch, Regulated LED headlamps,
    digital camera, etc.

    Some devices emit RF when turned OFF but plugged in an AC outlet.

    -notice non-regulated LED lights do not emit RF.

  13. #13
    Flashaholic*
    Join Date
    Feb 2006
    Location
    Ventura, CA.
    Posts
    2,025

    Default Re: How do I detect and measure RF/EM radiation?

    well for what's it's worth I know when the Navy is on high alert because they increase the radar power which causes tiny interference dots on my DTV screen.. they are tiny little dots, about the size of a period. "." and are distributed in a 'dancing' grid pattern across the screen.. it's ominous when they appear, sometimes at night, you wonder what they're searching for out there..

  14. #14
    *Flashaholic* James S's Avatar
    Join Date
    Aug 2002
    Location
    on an island surrounded by reality
    Posts
    5,081

    Default Re: How do I detect and measure RF/EM radiation?

    is it just a cell phone tower? Those things are pretty closely regulated and even with a bazillion people using transmitters a few inches from their brain the studies that might show an effect are still so close to the nose level that there is unlikely to be any real effect there. So your exposure by living near a tower where you're a lot further from the transmitters isn't likely to do anything bad to you at all even over the long term. At least according to any of the current data.

    you will want to read the wikipedia article on the Inverse Square Law and understand that your exposure will be very small.

    It's really not worth stressing over. If there were a real effect of living under the thing it would show up quite clearly on the data. Afterall there are a LOT of these things, especially in urban areas where people often live right inside an apartment with the antennas mounted right outside their bedroom windows.
    -James

    E=sqrt((mc^2)^2+(pc)^2)

  15. #15
    Flashaholic*
    Join Date
    Feb 2006
    Location
    Ventura, CA.
    Posts
    2,025

    Default Re: How do I detect and measure RF/EM radiation?

    the electrical activity of the brain is so tiny that the most sensitive instruments man has made are needed to measure the magnetic fields they produce outside (!) the brain. see the 'squid' device-- http://www.lanl.gov/quarterly/q_spri...uid_text.shtml

    a little research turns up much to indicate that magnetic fields applied to the brain most definitely affect thought, and even the ability to discern truth from falsehood. I can't help thinking that the immense magnetic fields present in everyday life both man made and cosmic have a profound affect on our brains..
    Last edited by TedTheLed; 11-18-2007 at 08:05 PM.

  16. #16
    *Flashaholic* PhotonWrangler's Avatar
    Join Date
    Oct 2003
    Location
    In a handbasket
    Posts
    10,962

    Default Re: How do I detect and measure RF/EM radiation?

    Quote Originally Posted by LowBat View Post
    I just want to get a general idea of exposure levels. It sounds like that trifield meter is about what I'm looking for.

    Thanks everyone!
    I've had a TriField meter for years and I like it. While it's not going to be anywhere nearly as sensitive as the labratory grade instruments, it will tell you if there's an unusually large amount of RFI or EMI in the immediate area.

    Having said that, RF energy falls off in intensity with the inverse-square law. In other words, as soon as it leaves the antenna, the field strength goes way, way down.

  17. #17
    Flashaholic* hopkins's Avatar
    Join Date
    Nov 2007
    Location
    California
    Posts
    906

    Default Re: How do I detect and measure RF/EM radiation?

    Hi Tedtheled - There was the scifi novel 'The Terminal Man' about putting
    wires into a guys head to control his violent seizures. No inverse square
    law reduction for that situation.
    Whats seems to true is that people can think themselves sick as well as
    spontaneously cure themselves, ie the placebo effect.
    So lets not worry about low power RF from flashlights.

  18. #18
    *Flashaholic* James S's Avatar
    Join Date
    Aug 2002
    Location
    on an island surrounded by reality
    Posts
    5,081

    Default Re: How do I detect and measure RF/EM radiation?

    Quote Originally Posted by TedTheLed View Post
    the electrical activity of the brain is so tiny that the most sensitive instruments man has made are needed to measure the magnetic fields they produce outside (!) the brain. see the 'squid' device-- http://www.lanl.gov/quarterly/q_spri...uid_text.shtml

    a little research turns up much to indicate that magnetic fields applied to the brain most definitely affect thought, and even the ability to discern truth from falsehood. I can't help thinking that the immense magnetic fields present in everyday life both man made and cosmic have a profound affect on our brains..
    they measure the miniscule magnetic effects because in order to measure the actual electrical (or chemical) signals they would need to open up your head and stick pins in your brain

    And yet we can put you in a MRI scanner with a magnetic field above 3 teslas (which is HUGE, big enough to pull an iron gas canister across the room and decapitate the tech standing next to the machine, this has happened and is one way that very large magnetic fields are really dangerous!) and you can sit there quite happily and the iron doesn't get pulled out of your blood (the iron as chemically bound in hemoglobin is completely 100% non-magnetic which is why anybody that wants to sell you a magnet to do something to your blood is selling snake oil) and the fields that run your thoughts inside your head remain completely unaffected by that.

    Then there is the fact that there is a bit of a difference between magnetic fields and radio frequency fields. These things all interact very weakly or not at all in any level you're likely to experience outside of a laboratory (or some of the folks around here in the basements ) Remember that the ability of microwaves to heat food was not discovered because of any effect it was having on people, but rather because the people working in operating radar dishes who were otherwise completely unaffected found that chocolate bars in their pockets would melt.

    You are not so sensitive to low levels of electromagnetic, radio or magnetic fields. The reason we have government agencies is to find out how much before there is an effect. They do a fairly decent job of protecting us from poisonous levels of all sorts of things. They generally find the lowest level from something for which it has been demonstrated that there is no effect, and then decrease what they consider to be the "safe" exposure level another order of magnitude or more below that just to be sure.

    So you're already being exposed to an order of magnitude less RF from those than has ever been measured to have any kind of effect at all.

    There was a really wonderful "stunt" pulled in the UK a couple of years ago. There are always people who are worried about the effects of a new tower. After a new tower went up in some town the locals were interviewed about how they think it affected their health. Many people did claim that it had made them dizzy or sick or increased pain or various other vague symptoms. The joke was that they hadn't actually turned it on yet. So indeed, you can think yourself sick, but the tower wont make you sick. Do not let yourself worry about it! Worry and stress are far more destructive to both your physical and emotional health than a little stray RF.
    -James

    E=sqrt((mc^2)^2+(pc)^2)

  19. #19
    Flashaholic*
    Join Date
    Feb 2006
    Location
    Ventura, CA.
    Posts
    2,025

    Default Re: How do I detect and measure RF/EM radiation?

    James, sure we notice when the RMI machine sucks up gas cannisters, or would notice if it pulled the iron out of our veins while lying there, but what about subtle, miniscule changes in thought itself? Nothing blaring and grotesque but just enough to confuse the line between right and wrong, (has been done in the lab) just enough to get you to think drinking that infamous glass of 'koolaid' would be just the thing to do right now..
    even if the guberment did know about such effects, would you trust THEM to inform you?

    and this minimalisation of the rf energy by quoting the square inverse law makes me wonder how come any Beethoven comes out of that little box at all..obviously some of the energy travels great distances to perform the miracle..

  20. #20
    *Flashaholic* James S's Avatar
    Join Date
    Aug 2002
    Location
    on an island surrounded by reality
    Posts
    5,081

    Default Re: How do I detect and measure RF/EM radiation?

    Quote Originally Posted by TedTheLed View Post
    James, sure we notice when the RMI machine sucks up gas cannisters, or would notice if it pulled the iron out of our veins while lying there, but what about subtle, miniscule changes in thought itself? Nothing blaring and grotesque but just enough to confuse the line between right and wrong, (has been done in the lab) just enough to get you to think drinking that infamous glass of 'koolaid' would be just the thing to do right now..
    even if the guberment did know about such effects, would you trust THEM to inform you?

    and this minimalisation of the rf energy by quoting the square inverse law makes me wonder how come any Beethoven comes out of that little box at all..obviously some of the energy travels great distances to perform the miracle..
    Beethoven comes out of the box because of the wonderfulness of the amplifier circuit which uses the miracle of the transistor or vacuum tube. Those are necessary to take the microvolts that the RF in the air are able to induce in the antenna and turn them into a voltage level which the rest of the system can work with You need the box because you have no tools built into your body to receive or listen to that kind of energy.

    Just because we are able to build a machine that can detect a thing it does not therefore follow that the levels we are able to detect cause an effect on our bodies. The dose makes the poison. There was a measurable amount of arsenic and cyanide in whatever you drank with your dinner, there is a measurable amount of botulinum toxin in the honey you put on your toast yesterday and there is a measurable amount of gamma radiation flowing through your body right now. But none of it begins to reach a level when it will have an effect on you. Pump the levels of any poison or toxin high enough and it becomes toxic and poisonous but it does not necessarily follow that therefore any detectable level of those things is bad for you.

    There is actually some good data now that shows that very long term high level exposure to cell phone radiation might cause the level of harm to rise above the noise level. Greater than 10 years of headset use daily. But its still hard to see. Science isn't bad at finding these things. They can measure very very small effects given a large enough sample and yet these kinds of exposures still do not rise above the noise far enough that they are certain there is anything there at all. But, instead of trying to cover it up and join a vast governmental conspiracy instead they publish their data in the open and continue to gather more data to try to answer the question once and for all.

    I know the government and many folks at various universities have experimented with inducing mental things by injecting rf and mangetic energy directly into the brain. There was that guy at some university that can induce both the sensation of intense religious epiphany and feeling that "this means something!" even when it doesn't. But that doesn't mean that those signals can be broadcast from a cell phone tower. It requires more resolution to your head than that, you have to wear a helmet covered in electromagnet coils

    I dont know about you, but most RF energy passes right through me without any effect at all. My brain relies on both chemical and ionic/electrical methods of sending pulses around that are not so easily disrupted.

    Nope, I'm not buying that it does anything to you until somebody shows that it does. Someday the government might pull out it's less-lethal crowd control fear generator gun based on some RF technology, but thinking that they can do anything to you through a cellphone tower is more suited to a novel... perhaps I'll write a novel about it
    -James

    E=sqrt((mc^2)^2+(pc)^2)

  21. #21
    Flashaholic*
    Join Date
    Feb 2006
    Location
    Ventura, CA.
    Posts
    2,025

    Default Re: How do I detect and measure RF/EM radiation?

    James, I didn't mean just cell phone towers, but, what IF cell phone towers made SOME people a little more nervous, a little more suspicious, angry,
    paranoid, or depressed? Again I'm not talking tumors and death here, but subtle personality changes.. How would we possibly notice or discover this without a thorough campaign of questioning and examination of the people and the lives they live around the towers?
    The only government I've heard of that actually asks it's subjects how they are feeling is the Tibetan, and they just want to know if you're happy.

    There IS an experiment that has been done, with the subjects wearing helmet devices that generate very mild magnetic waves, that DID change their perception of truth and falsehoods. The waves affected what was called the "repudiation effect" of the brain, that is they eliminated it, so what a subject would normally say is false, they say is true under the waves affect -- I'll try to find it. Just saw it yesterday on TV..

  22. #22
    *Flashaholic* PhotonWrangler's Avatar
    Join Date
    Oct 2003
    Location
    In a handbasket
    Posts
    10,962

    Default Re: How do I detect and measure RF/EM radiation?

    I know a guy who claims that he gets disoriented by strong magnetic fields.

    This was somewhat "confirmed" when a co-worker who knew about his claim brought a large, powerful magnet within an inch of the back of the guy's head without his knowledge. He immediately became disoriended without knowing why.

    You decide...

  23. #23
    Flashaholic*
    Join Date
    Jan 2006
    Location
    Los Angeles, Calif.
    Posts
    1,470

    Default Re: How do I detect and measure RF/EM radiation?

    I work for a company that manufactures high-power RF amplifiers. RF exposure is not a concern here, but RF burns are.

    Medical MRIs use very high-intensity RF fields to induce proton spin. They do not consider this to be a hazard because it is non-ionizing ("radioactive") radiation.

    However, that does not mean *I* trust "them" hahaha. While online Christmas shopping yesterday, I came across the Ramsey Tri-Field Meter kit. It's the lowest-cost tri-field meter I've seen @ $65.

  24. #24
    *Flashaholic* James S's Avatar
    Join Date
    Aug 2002
    Location
    on an island surrounded by reality
    Posts
    5,081

    Default Re: How do I detect and measure RF/EM radiation?

    And if you do pick up the meter and find their output to be out of spec from what is allowed, you can call in the authorities and get them slapped with some not-insignificant penalties. So check up on them if you're interested, but dont be worried just because some RF is passing through you!
    -James

    E=sqrt((mc^2)^2+(pc)^2)

  25. #25
    Flashaholic* hopkins's Avatar
    Join Date
    Nov 2007
    Location
    California
    Posts
    906

    Default Re: How do I detect and measure RF/EM radiation?

    Hi Lowbat
    Recently noticed that when our neighbor turned on their laundry room fluorescent light AM radio reception was scrambled by loud 60hz buzzing.
    I went over with a new ballast, explained to her the problem and got a free
    drink after the repair.

    Einstein said:
    You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat

  26. #26
    Flashaholic* BigusLightus's Avatar
    Join Date
    Jul 2006
    Location
    Down the street from Cree HQ in Durham, NC
    Posts
    521

    Default Re: How do I detect and measure RF/EM radiation?

    LowBat,

    The simple answer is to check the web and find the local Ham Radio Club. There will be some serious radio geeks there with serious equipment. They will be able to help you out and they will probably find it to be an exciting challenge.

    James
    KF4WXH
    My favorite flashohol suppliers are: AW, FiveMega, NailBender, MalkoffDevices, 4Sevens, GoingGear, BatteryStation, EDCplus, SBflashlights, TacticalSupply, LightHound, and Action-Lights.

  27. #27
    Flashaholic* LowBat's Avatar
    Join Date
    Jan 2005
    Location
    San Jose, CA
    Posts
    2,524

    Default Re: How do I detect and measure RF/EM radiation?

    Wow, I'm surprised this thread is still going. I no longer have a need for a detector as the place I was thinking of moving to (lots of antennas and electrical equipment) didn't happen. I do thank you all for your input.

  28. #28
    Flashaholic
    Join Date
    Aug 2006
    Location
    Waynesboro, Pa FM19es
    Posts
    366

    Default Re: How do I detect and measure RF/EM radiation?

    Quote Originally Posted by BigusLightus View Post
    LowBat,

    The simple answer is to check the web and find the local Ham Radio Club. There will be some serious radio geeks there with serious equipment. They will be able to help you out and they will probably find it to be an exciting challenge.

    James
    KF4WXH

    Yes, what you are looking for is a field strength meter. Do not use an AM transistor radio for this purpose as it will be prone to front-end overload. Find out what is on this tower we may be able to help with that info.

  29. #29

    Default Re: How do I detect and measure RF/EM radiation?

    While keeping the "inverse square law" in mind, there are antenna directional characteristics to consider. Most high power transmitters feed directional antennas. In these cases there may be less radio frequency emissions close to the bottom of the tower than there are when you move a slight distance away, at that point the inverse square law comes into effect. The frequency of the emissions determine the distance from the tower that you start to receive full power with respect to the type of antenna. If you are close to a tower, you can get the radiation info from the engineering department of the antenna owner. All commercial antennas are registered with the FCC and they also have this info.

    PS: I know that the plural term for antenna is antennae (I'm just trying to keep it simple)

  30. #30
    Flashaholic* Steve K's Avatar
    Join Date
    Jun 2002
    Location
    Peoria, IL
    Posts
    1,985

    Default Re: How do I detect and measure RF/EM radiation?

    Quote Originally Posted by hopkins View Post
    Einstein said:
    You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat
    I forgot about that quote.. I may have to name my next cat "Ether".
    (my current cat is named after Tesla)

    Steve K.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •