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How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/20/2011 7:17 AM

Dear people,

is there somebody who can help me please to find an machine to mesure electromagnetic fields between 400 and 450 MHZ? I need somethink easy to take with me and not to expencive.

Thanks,Rebeka

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#1

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/20/2011 11:20 AM

Try this Google link

It turned up 178,000 results.

Don't know if any will help but it is a place to start.

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#2

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/21/2011 5:05 AM

A better google search would be for "handheld spectrum analyser"

That search was done for the UK I suggest you repeat it for your own location.

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#3

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/21/2011 9:52 AM

Rebeka

Welcome to CR4

It is going to depend on what you want to measure and how accurate the measurement needs to be. Simple meters can measure the frequency of a signal if that is all you want to know. Some of the hand held equipment can display transmission/reflection measurements, but the accuracy may not meet your requirements.

With RF signals, sometimes a little knowledge can a dangerous thing. Have you had any field, transmission line or propagation theory courses or experience? It could help us give you a better answer.

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#4
In reply to #3

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/21/2011 1:18 PM

Dear U Know Who,

I don´t have any theory courses or experience and would like know more about. But I really want to mesure the electromagnetic fields around me to protect myself. I am investigating about the dangerous electromagnetic radiations. The information I´ve got trough internet is: The natural puls rate of the Earth is 7.83 Hz. 10.80 Hz causes riotous behavior, 6.6 Hz causes depression. 400-450 MHZ is the window to human consciensness. Our brain works between this electromagnetic fields.

I need to find a simple but very effective measure instrument (with the possibility to connect the data to internet) to measure if there are some of the radiations I mentioned above.

Thanks for you effort to help me,greetings

Rebeka

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#5
In reply to #4

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/21/2011 2:40 PM

Rebeka

Don't mean to alarm or confuse you, but electromagnetic waves are around us all of the time! The level is usually so low in power that it is not harmful, and it takes a very sensitive receiver tuned to the specific frequency (or an expensive & sensitive receiver sweeping the bands desired) to detect their presence. The technology unfortunately does not lend itself to "inexpensive".

The 400-450MHz band you seek is above the AM/FM radio & TV bands (except for UHF TV) and below the telecommunication (cell phone), mobile radio & satellite communication bands, so there should not be significant activity (or specific equipment available) in this spectrum. I know what you need, but I am not aware of any low cost solutions available........sorry!

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#6
In reply to #5

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/21/2011 3:45 PM

Hello,

thanks for your answer. If I understand you, may I need to buy expensive

equipment? Could you tell me where I can find it?

Rebeka

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#11
In reply to #6

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/25/2011 8:08 AM

Some people protect them self, from what they consider dangerous electromagnetic waves, wearing a special hat. They manufacture this hat them self. It requires a paper cone, with the base diameter to fit on your head. Than, they cover the cone with aluminium (AL) foil. Here are two distinct opinions about the AL foil. The first one says that it should be new, unwrinkled AL foil, which has a stronger reflection capability. The second urges the use of wrinkled AL foil, which scatter the electromagnetic waves, with multiple benefits for large families.

Males should wear underwear made in the same technology.

The problem is that most of the people who do not wear such protective devices, consider those wearing them, a little....odd!

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#12
In reply to #11

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/25/2011 12:28 PM

Hello,

it is funny what you say and I dont know if I should believe. Can you send me some link on the internet with those people who use that hat?

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#14
In reply to #12

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/25/2011 12:52 PM
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#15
In reply to #14

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/25/2011 5:21 PM

Hmm I'm not at all sure about this. Suppose you were wearing one in bed with your feet pointing towards a transmitter. The hat would effectively focus all the power from a seven inch diameter circle on a single spot in the middle of the brain.

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#16
In reply to #15

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/25/2011 5:41 PM

Good observation! This is the reason you should use wrinkled AL foil!!!

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#7

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/21/2011 6:44 PM

Go out to the internet and search for a BIRD 4041 relative field strength meter. They are hand held and not too expensive. since they are older they should be available as surplus. They measure field strength from 1MHZ to 1000MHZ. It will not tell you the exact frequency but it will tell you the strength. Any field strong enough to hurt you in this frequency range can be picked up by this meter.

There are other brands that will do this too. I am just familiar with this one. I have two sitting on my desk.

If you are willing to put a kit together Ramsey Electronics has a kit, part number TFM3C that should work for you. This would give info on where a field is and its "relative" strength but is not calibrated for actual strength. it is a kit.

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#8
In reply to #7

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/22/2011 5:16 AM

Thanks for your advise! I wil have a look to this kit!!!

Happy Easter to everybody!!!

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#9
In reply to #8

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/22/2011 8:07 AM

The radio door bell I just fixed works at 418 MHz. The most harmful piece of radio gear around is the mobile cell-phones people use daily. Because you hold it right on your ear around half the transmitted power is absorbed by your head. This is far more power than you will ever get from a "phone mast" (or any other incidental pick-up from transmitters).The usual frequency is about the same as a microwave cooker. There has not, so far as I know, been any real positive evidence that radio exposure is a hazard for the ordinary person, until last year. A study of frequent mobile phone users found their incidence of brain tumours was higher than normal. That does not make positive evidence, there are so many factors possible - but they found the majority of the brain tumours were on the side they habitually held their phone! But as I wrote, holding a transmitter right against your head is the worst risk - the field strength with the transmitter 1 metre away would be 1/100 or less - the inverse square law fall with distance from transmitter applies.

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#13
In reply to #7

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/25/2011 12:31 PM

Thanks a lot for your help!!!!

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#10

Re: How to Measure Electromagnetic Fields between 400 and 450 Mhz

04/23/2011 12:52 PM

You will need a CALIBRATED antenna to connect to a good portable spectrum analyzer (SA). FOr the antenna, you might investigate the BicoLOG® 5070, which covers your F range. For the SA, I would start with the Tektronix SA2600 (but many others are available, e.g. Agilent, Rhode and Schwarz, Anritsu).

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67model (1); Anonymous Poster (3); KJK/USA (1); Randall (2); rebeka (5); silvCrow (1); U NO WHO (2); WoodwardDL (1)

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