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Antenna Design to Capture Atmospheric E-field Gradient

epsolutions

Sep 7, 2019
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I would like to erect a tall antenna to tap into the Earth's atmospheric e-field potential relative to ground. Theoretically, this can be hundreds of volts per meter. The process is also known as "ion harvesting".

What I had in mind was a 20 meter length of cable with pointed spurs or wire grid at the top hanging from a tree or building. At the bottom there would be a HV rectifying diode, with sensitive measuring instruments between that and an electrical ground stake.

This is purely for small scale demonstration and not to power ES motors, charge cap banks, etc. Practical uses include storm prediction.

Questions:

Does the cable need to be shielded between top and bottom? For example in the form of grounded coax full length or single wire on insulating standoffs. Even a wood pole becomes conductive when wet.

Is a single diode sufficient, or is there a better way of maximizing accumulated voltage potential? However, please note that this is not a tuned circuit. I am not targeting specific technological frequencies but rather the natural atmospheric DC potential.

Any general insights on this topic would be most welcome.
 

Externet

Aug 24, 2009
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Why do you choose 20m vertical ? A loooong wire (as an existing barbed wire fence) with rectification at the end would not convince you ?
 

epsolutions

Sep 7, 2019
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As I mentioned, this is not about "energy harvesting" per se but rather voltage measurement. In other words, a detector of variations in the atmospheric e-field gradient ... which is vertical. Hence the vertical antenna. My question related to configuration of the antenna and rectification for DC measurement. The theoretical gradient is about 100V per meter in height. This changes under geophysical conditions.
 

Externet

Aug 24, 2009
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This does not compute...
"100V/m in height" That is huge ! A vertical conductor antenna is a conductor. Conducts. How can it show a gradient if the potential is in a conductor showing the same voltage at all its length - because it conducts ! The potential at the top end is the one that will be measured at the bottom -- because it conducts ! o_O I do not get it...
 

epsolutions

Sep 7, 2019
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The vertical wire may have the same voltage all its length, as determined by height, but that is referenced to ground or "zero" volts, not the wire itself. Or am I missing something?

Apart from that, people have done this successfully before to power small motors, etc. Any answers to my original questions?
 

epsolutions

Sep 7, 2019
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Here is a video that explains the principal probably better than I have. However, as previously mentioned, I am not interested in powering devices. I just want to measure the current variations in the wire. The proposed diode would be to nullify any AC effect.

 

Nanren888

Nov 8, 2015
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It's essentially DC. Not sure what AC you want to block. I'd suspect that any AC signals, right up to the point htat you get hit by lightning, may be too small to bother about.
What sort of thing are you doing the measuring with? It will need a reasonable input impedance.sensitive, sure, ok, I guess you mean high-impedance?, it has to measure potentially large voltages.
As in the video, a conducting wire will take earth potential,or whatever the other end is connected to with it, so. one option is to take coax up & just extend the centre higher, thereby measuring the gradient; the difference between where the shield is and where the extended inner is?
If you have any idea of going to height, bear in mind that the voltage may get high. That corona off the end may tend to create ozone, which you probbably shouldn't get too much of.
Antenna? Not sure you need anything special for DC.
Dragging a wire up with a drone, is not a bad idea. The drone may generate some static though. Depends on how exacting you want to be.
 

epsolutions

Sep 7, 2019
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Thanks. All good pointers. I was concerned about RF, or picking up some strange submarine transmission ;-)

The measuring device will require more investigation. High impedance. High voltage. Any ideas?

Yes, I was thinking of 50 ohm coax, but the top end needs lots of points (not just one) to efficiently dump electrons into the atmosphere.

Here is a video of someone using a drone.
 

Bluejets

Oct 5, 2014
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If I remember correctly , there was a device used in rc aircraft way back when ( pre-1980's) that used small radio active components from old smoke alarms as a reference for level flight using the earth's vertical voltage differential.
These days it's much more user friendly with component modules with everything done so-to-speak for a couple of dollars from China.
Free energy...!!! OMG...that's it ...good luck staying out of solitary.
 

Nanren888

Nov 8, 2015
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Ok, on principle, I object to the teaser image of holding up a glowing incandescent bulb. Electroscope, ok, corona motor, ok,
At a risk of extra o3, much larger corona motors are possible, but never seen one with any significant torque to speak of.
.
he top end needs lots of points

If you just want to measure the voltage, I suspect that you don't need lots of sharp points.
If you want to draw any even minute power, then ok, a little more current-carrying capacity may help.
 

Externet

Aug 24, 2009
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...At the bottom there would be a HV rectifying diode, with sensitive measuring instruments between that and an electrical ground stake...
...The proposed diode would be to nullify any AC effect...
...The vertical wire may have the same voltage all its length, as determined by height, but that is referenced to ground or "zero" volts, not the wire itself...

Would the proposed diode be to "nullify" or to rectify AC from transmitting radio stations ? There is no other AC in the air I can think of...

If you insert the negative lead of your digital multimeter into the soil and extend the leads vertically with the positive lead all the way up in the air, the total length will be around or more than 1 metre. Do you think the multimeter will read 100 V ?
 

Nanren888

Nov 8, 2015
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Effective input impedance of an electroscope might be a little higher than even a good dvm.
 
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