Text Book on Ambient EMF Measurements

[[email protected]]

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

 

[Fred Abse]

Is this what you're doing?
<http://www.smartertechnology.com/c/...t-Monitors-Benefit-from-RF-Energy-Harvesting/>

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.

 

[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?

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.

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.

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

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.

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.

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.

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.

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.

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

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

That dog won't hunt.

 

[tm]

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.

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

tm

 

[John Devereux]

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

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

 

[Fred Abse]

At what point is the amount allegedly stolen considered to be
sufficient to be considered damaging.

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.

It would be interesting to see how the owner could recover possession.

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

 

[Fred Abse]

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

Frequency?

Receiving antenna aperture?

Show your working.

 

[Tim Williams]

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.

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

 

[Robert Macy]

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

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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[John S]

On Sun, 24 Mar 2013 08:08:21 -0700, Fred Abse

On Sat, 23 Mar 2013 20:16:58 -0700, Jeff Liebermann wrote:

Is this what you're doing?
<http://www.smartertechnology.com/c/...t-Monitors-Benefit-from-RF-Energy-Harvesting/>

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

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

[...]

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

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
http://siliconflatirons.com/documents/Roundtables/2011.10.18-1021/FCCAuthorityMemo.pdf

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. <grin!> )

and this blog entry:

GAO Receiver Report
http://www.marcus-spectrum.com/Blog/files/tag-receiver-standards.html

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. <grin!>


Frank McKenney

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

 

[brent]

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..

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.