60 Hz RF

A horizontal dipole very close to ground (in terms of wavelengths) is extremely inefficient RF radiator.

A 1250 km high _vertical_ radiator would be quite efficient.

Excellent answer, and ( in the form of degaussing coils) easily available as off-the-shelf hardware. Not terribly well designed for long range radiant emission, but that wasn't in the original requirement, anyhow.

Wait a minute. Maglev on a pair of spinning bar magnets? Wouldn't they cancel each other out?

Thanks, Rich

Hey. We have enough problems with eagles nesting on power poles. The Society for the Prevention of Cruelty to Satellites will go berserk when satellites start nesting on your antenna.

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Take the pebbles out.

Actually, half that would still be relatively efficient. Ground conductivity would eat up some in either case.

I suggest the OP go to the nearest tower owned by a TV station and shunt feed it. Let us know how it goes for you.

Use the whole electric distribution network as an elevated ground plane.

A stratospheric balloon at 30 km carrying the vertical conductor and additional balloons at the same altitude carrying other horizontal wires as the top loading capacitance might give something like 0.01 % efficiency.

On a sunny day (Sat, 23 Jul 2011 02:00:51 +0000 (UTC)) it happened Shiny Side Down wrote in :

Most satellites are much higher up, say 40000 km for geostatic, At 1250 kM there may perhaps be some air too to break the speed?

There is a tin can at 350 km (ISS).

Sun synchronous weather satellites at 600-800 km.

On a sunny day (Sat, 23 Jul 2011 15:42:12 +0300) it happened snipped-for-privacy@downunder.com wrote in :

Right, that space station fubar needs periodic boosting to compensate for the orbit change due to air restance.

Did not know about that. Maybe you can hang an antenna from one of those ;-)

>

"Sun synchronous" means a polar orbit (typically 2-3 h period) that flies over a certain place on earth at the same local time each day, thus he illumination conditions are the same each day and pictures from different days can be easily compared, which is important for weather and spy satellites.

By no means are these satellites stationary.

The proposed Space Elevator up to the geosynchronous orbit would be a nice vertical radiator but IMHO, it can never be built, due to the huge number of satellites, spent rocket stages, bolts and paint flakes orbiting the Earth and sooner or later hitting the space elevator.

It's actually a little retrograde; have to make up for the Earth's orbit.

Geosync satellites can't view a large percentage of the important targets.

Let's not forget physics and materials science.

On a sunny day (Sat, 23 Jul 2011 18:35:44 +0300) it happened snipped-for-privacy@downunder.com wrote in :

The other thing is you could make a big loop around the earth in space. Should it move? How would it interact with the earth magnetic field? Maybe in some NS orientation it would just stay up there, or work as a giant dynamo, *free energy* :-)

Side

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It ought to work. Th earth iron core should enhance the antenna quality enormously. The antenna should occupy a wider orbit then the ISS , to avoid interference. Anybody able to guessimate its selfinductance?

It's obviously efficient enough - have you ever touched a scope probe with your finger?

Cheers! Rich

The radiator from a radiator extremely close to the ground plane (in terms of wavelengths) and the radiation from the "image" below ground plane will cancel and hence, very little electromagnetic waves will be observed in the _far_ field.

This is a _near_ field phenomenon or actually electric field phenomenon.

The stray capacitance between the human body and the room (and the embedded mains wiring) is typically in the order of 10-100 pF, thus at mains frequencies, the capacitive reactance is about 100 Mohms. With scope input resistance of 1 Mohm, there is a 100:1 voltage divider.

With 100-240 V mains voltages, the scope input voltage would be about

1 Vrms.

Any harmonics and other interference riding on the mains voltage will pass through the stray capacitance more easily, distorting the waveform shown on the scope more than the distortion was on the mains.

OK, so build a 625 KM tall quarter-wave tower.

Good Luck! Rich

OK Question for you. The ionosphere is only a short distance away(by wavelength) and the ionosphere to ground volume creates an 8 wavelength cavity around the earth. The distance is also short compared to the length of radiator.

How efficient would the coupling from the power lines to that be?

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Take the pebbles out.

I guess he'll have to put his antenna on the moon. ;-)

Cheers! Rich

The Schumann resonance will quite effectively propagate the electromagnetic radiation from lightnings.

With antenna "conductor" lengths of several kilometers and "antenna currents" in the order of 10-100 kA, there is going to be quite a lot of radiation, since the strike peak power is in the order of terawatts.

I have no idea how strong the upper atmosphere lightnings (sprites, jets, elves) are, but they are up to 100 km long (from the cloud to ionosphere).

You could try to measure it. In the US try to receive 50 Hz radiation from Europe or in Europe, try to receive 60 Hz radiation from the US. The various networks are not all the time spot on at the nominal frequency, but varies slightly during the day, depending on the load. For instance, the Scandinavian network instantaneous frequency can be seen from here

(currently 49.98 Hz), thus with sufficient integration times, you should be able to detect separate peaks from different networks around the nominal frequency, if the radiation is transported across the Atlantic.

Please note that the high and medium voltage systems are three phase (as well as most of the low voltage distribution in Europe), thus, any external fields a few hundred meters from the line will cancel out, since the instantaneous currents in the phase currents flow in the different direction and thus the external fields cancel quite well.