Text Book on Ambient EMF Measurements

Can anyone suggest a good text book, or online publication, that explains in detail the procedures for detection and measurement of ambient RF?

IOW out in the field, not in the lab.

Our antenna guy just passed away, so we need to get up to speed on this.

Thanks for any advice.

Richard Jones

Reply to
rjones23
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AFAICS, energy harvesting from RF fields could be regarded as theft.

It is impossible to remove energy from a field without disturbing that field.

The field was put there, *and paid for*, by someone else, with a specific purpose. The owner has the right to expect that field not to be deliberately disturbed.

Extracting energy can be said to be depriving the owner of his property, for the gain of another.

Ambient RF energy is not a free resource. Somebody bought and paid for it.

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Reply to
Fred Abse

Any innovative and useful application of technology can be screwed up by the judicious application of legal hairsplitting.

Amazing. Does that mean when I turn on my AM/FM/TV radio, the transmitting station sees a dip in RF output power?

True. However, who owns your garbage? You paid for the products you throw away. Do you still claim ownership when the refuse is salvaged and re-used. Same with radio transmissions. The RF being generated was paid for by the radio station. However, the 99.999999% of that energy, that is not captured by the receiving antenna, is wasted on heating up the environment, and polluting the airwaves. The station own can probably sue for misuse of his RF energy, as in theft of service from the power company, but I don't believe the FCC or any court of law will take the case seriously. One also has to identify the source of the revenue loss. Since RF energy scavenging devices are not selective, there is no way to determine which radio stations are powering the device, or allocate a fair distribution among various stations.

In order to be considered injured, one must demonstrate to the court the extent of the loss and demonstrate loss of income or added expenses incurred as a result of said loss. Most such free energy devices produce a few milliwatts of detected power. It would be interesting to award damages based on recovering 50 milliwatts of RF from a 50,000 watt transmitter.

Efficiency of a modern 50,000 watt AM transmitter is about 80%. 63KW of power, for 1 hr, will cost about $0.20 per kw-hr, or about $12.60/hr or $302/day. So, the loss of 50 milliwatts of scavenged power from this radio station would cost: 0.050 watts / 50,000 watts * $302 = $0.000302 /day or $0.11/year. I suspect the cost of collecting the $0.11/year from users of the devices would be more than the recovered "lost" revenue.

Yep.... and "fair taxation" is an oxymoron.

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Reply to
Jeff Liebermann

Of course not. The intrinsic impedance of free space is 120*pi ~ 377 ohms, but I guess you knew that,already.

Measure the field in front of, and behind a receiving antenna, and you'll see the difference.

No it isn't garbage, it's a necessary part of an operable system.

The station own can probably sue

Stolen goods are stolen goods, even if you can't identify the owner. The act of appropriation with intent to deprive someone else of lawful benefit is sufficient. It's not an FCC matter, it's purely common law.

You admit that it's not selective, what then of ten thousand users each trying to extract 50 milliwatts from the field of a 500 watt transmitter?

Damages aren't the issue, it's a criminal, not a civil matter. Unlawfully taking with the intent to deprive the owner of possession.

I repeat, not a civil damages matter. No less criminal than extracting energy from fields surrounding transmission lines.

That dog won't hunt.

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Reply to
Fred Abse

If you are getting 50 mW from a 500 W transmitter, you are trespassing.

tm

Reply to
tm

I've never actually tried it, but I assume that if an antenna can extract a few micro or millwatts of RF from the transmitted signal, there would be a corresponding reduction of field strength. Actually, I did try something like that once. I put two yagi antennas in line with each other, separated by several wavelengths. The signal levels were identical but then I wasn't looking for microwatt differences. I was trying to find the optimum stacking separation and was having some fun trying weird things. Somehow, the loss of a few microwatts out of

50,000 watts is unlikely to affect service to other users.

Please explain how RF energy, that is not being received by anyone, is part of an operable communications system. It's more like a side effect or uncontrolled consequence of the transmission system, which is more like garbage than anything of value.

Ignoring the current fashion of revenue enhancement by confiscation and ignoring controlled substances, as I understand it, an object is not considered stolen unless an owner can be identified. In this case, it would be difficult to arrive in court with the evidence as a bag or box of allegedly stolen RF waves.

Good point. At what point is the amount allegedly stolen considered to be sufficient to be considered damaging. It's much like the middle east, where burying long wire antennas under power lines to pickup AC power by induction was considered theft. It was never really decided in the courts because the major transmission lines where this was practical had switched from AC to DC transmission, where a transformer would not work. I think we can safely leave it to the legislative machinery to establish a suitable dividing line.

It would be interesting to see how the owner could recover possession. The issue is covered under theft of services, usually in reference to cable TV, satellite TV, and telephony, where a real loss of revenue can be demonstrated. However, unless the broadcast industry switches to a subscription model, it would be difficult to demonstrate damages to an essentially free service.

And I repeat... show me the evidence of damage, where the radio station has lost revenue, listners, or quality of service.

Incidentally, the milliwatts is the optimistic power that the researchers hope to achieve. Currently, they're in the microwatt region, which is where I expect them to remain. That would make a claim of damages to be about 1000 times less in value.

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

To the same extent that using my house as a transmission route could be regarded as trespass :)

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John Devereux
Reply to
John Devereux

Whether you steal a Popsicle, or a million dollars, in law it is still theft, with punishment that may or may not be commensurate, depending on the jurisdiction.

In many cases, the owner never recovers possession, the thief having spent the proceeds, but the thief still goes to jail.

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Reply to
Fred Abse

Frequency?

Receiving antenna aperture?

Show your working.

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"For a successful technology, reality must take precedence  
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Reply to
Fred Abse

In a court of law, the victim or police can usually produce the popsicle, cash, or paper trail in evidence. If there are witnesses to the ingestion of the popsicle, that is often sufficient. However, producing the evidence is not possible with theft of RF. Having victimless crimes is bad enough. Now you want crimes without any evidence? I don't think so.

Sure, but that's because the thief was convicted as a result of an evidence trail, usually a paper trail. Thieves usually don't go to jail as a result of hearsay witness testimony where there is no tangible evidence of a theft even having taken place. (Reminder: In a civil case, the jury decides by the preponderance of evidence. In a criminal case, the jury has to be unanimous to convict). Finding a jury that takes this "crime" seriously may be rather difficult.

Whether delivered via RF or directly from the sun, all such power originates in the sun. You'll soon hear from the sun's attorney about your theft and misappropriation of solar energy.

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

The FCC is empowered by the US government to control RF access to your house. In effect, your acceptance and participation in the US republican system includes an easement by which any broadcaster can cross your property without your permission. There are rules that limit how much RF can trespass your property as excessive amounts might be dangerous. There are also rules that insure that you are supplied with a recommended minimum dose of RF powered entertainment by public broadcasters in your service area. Do try to appreciate all the things that the government is doing on your behalf.

This actually was a problem in the early days of broadcasting, where several states were considering taxing the reception of out of state stations. The point is somewhat similar to current argument. If RF crosses a state line, someone will need to pay. Obviously, this never went past the proposal stage.

Oh, you're in the UK. Never mind...

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

Some strange taxation methods were considered early on. Apparently there was a tax per tube law in Germany I think, so they invented the forerunner of the MK484 radio-in-one. Vacuum sealed resistors and several tube sections all in one envelope, just add coils. Although the production costs, as you might imagine, were more than a bit worse than the tax itself, so it never went into production.

Tim

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Reply to
Tim Williams

Again? Have you forgot about ON TV (OTA Subscription), or Zenith's pay radio services in the '60s?

Cincinnati was on Ch. 64, WIII, (The Eyes of Cincinnati)

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Reply to
Michael A. Terrell

I didn't want to include anything that was out of business or not currently available. Duz this look familiar: (I dunno why I still keep it around.) Those were all pay-TV providers, where building a bootleg receiver and decoder would be considered theft of service. However, rectifying their RF carrier to power some device, would not qualify as the pay-TV provider as they could not demonstrate a financial loss or content copyright infringement.

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

join the IEEE group that discusses these matters and post your question there. it's a combination of safety AND EMC, most of the questions appear to be about EMC. you'll get answers that'll make you think everything from 'say what?!' to "wow! didn't know that!"

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Reply to
Robert Macy

[...]

On the other hand, one might be considered to be extracting energy which the "transmitting agency" was "dumping" one one's property. At what point does this fall into the category of "unsolicited merchandise"?

( I'm assuming that all of the extraction equipment -- antenna, electronics, etc. -- is on private property. )

Hm. If one fills oxygen tanks from the air surrounding one's house, is one "stealing" from everyone one Earth? ( Could air-polluters be sued by "Gaia"? Ack! )

Oh. Does the FCC regulate non-radiating receiving equipment?

This opinion:

FCC?s Authority to Regulate Receivers

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says "When applying the case law and looking carefully at the statute, I think it is possible to find a legal justification for the FCC to exercise ancillary jurisdiction over receivers. It may, however, come down to popular opinion..." ( Sounds like a lawyer. )

and this blog entry:

GAO Receiver Report

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discusses a recent GAO report and its conclusion that the "FCC in general lacks authority to regulate receivers".

Sounds like a church key and a can of Nightcrawler suds.

Frank McKenney

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Reply to
Frnak McKenney

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Aren't they already regulating receivers? I think it is illegal to manufacture cellular frequency receivers. Yes?

Reply to
John S

The ban on receivers that can receive cellular and cordless phones is a Federal law in addition to an FCC rule. Various states also have laws regarding the posession and use of mobile scanners, radar detectors, and cordless phone monitors, all of which are receive only. Most of these laws arrived immediately after someone recorded and released a rather embarassing cell phone conversation. None of the stories about the incident bother to mention the exact equipment used to receive the cell phone conversation (for good reason as it was probably a comm service monitor with call progress detection and tracking software that could follow frequency jumps).

The FCC rules outlaw the manufacture, not the possession, of receivers that are capable of receiving cellular and cordless phone convesations. They also regulate incidental radiation (Part 15) from receivers, as well as non-radio devices, such as switching power supplies, monitors, TV's, general electronics, etc. In short, anything the *MIGHT* generate RF noise is tested and certified by the FCC.

One could argue that the reception of ambient RF power might in some way produce unwanted RF radiation as frequencies that were not originally present, as in RFID devices. In that case, the device would require Part 15 certification.

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

.
   (Richard Feynman)

When I first started my career I worked with a guy who was at the very end of his career. He did a lot of radar work during WWII in England. He had a story about a radar they had set up and they knew the antenna pattern was not behaving the way it was supposed to. He said it turned out that a nearby farmer had somehow figured out how to run a big loop of wire through his barn (near the antenna) and was somehow able to generate power to light bulbs in his barn. Needless to say, the gov't made him take down his free power generating station.

Reply to
brent

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