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Author Topic: Using the Earth as an Antenna  (Read 7725 times)

Offline Swede P

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Using the Earth as an Antenna
« on: November 04, 2011, 2004 UTC »
Perhaps many have heard of this concept and already know it to be bunk, but I have run into a suggestion that instead of putting an antenna in the air, that one should use the earth itself as an antenna. The claim is that using the earth itself works better as the earth is more conductive. So instead of connect the earth to the GND terminal, it should be connected directly to the ANT terminal.

I can't help but to think that if this would really work then I would see it everywhere, but I don't see it anywhere. Still curiosity will get the better of me and I will experiment unless one of you fellows has tried it already or otherwise knows about it and can tell me if there is any truth to this theory.

Seeing that I live in a block of flats, I really want this to be true. Still, I have to face the reality.


Offline ChrisSmolinski

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Re: Using the Earth as an Antenna
« Reply #1 on: November 04, 2011, 2027 UTC »
The problem (well, one of them) that I see with this idea is that your radio's front end (antenna input) is looking at the signal across two terminals: the antenna input, and ground. The ground on a radio is connected to electrical ground in your house wiring, which then (for safety reasons) is connected to the earth through a ground. If you connect the antenna input to earth, you've effectively shorted the antenna terminals, at DC anyway. At RF, due to the various impedances involved, it won't be a short. But it certainly doesn't sound like it would be very effective.

I would expect that at some frequencies, you may get good reception, because the various impedances and wire lengths involved will work out to be if not ideal, at least reasonable. It's possible that some people have tried this, and lucked out that on a few frequencies they tried, it seemed to work. But yes, I'm skeptical also.
Chris Smolinski
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Re: Using the Earth as an Antenna
« Reply #2 on: November 04, 2011, 2244 UTC »
Alas, earth antennae are only feasible for V/U/ELF frequencies.

Cheers!

Offline Swede P

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Re: Using the Earth as an Antenna
« Reply #3 on: November 04, 2011, 2302 UTC »
"The problem (well, one of them) that I see with this idea is that your radio's front end (antenna input) is looking at the signal across two terminals: the antenna input, and ground."

Would it make any difference, in this regard anyway, just to connect the ground wire directly to the telescoping antenna?

Offline Lex

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Re: Using the Earth as an Antenna
« Reply #4 on: November 05, 2011, 0238 UTC »
Even a proper earth ground will work pretty well as an antenna for some frequencies, presumably because the combination of the length of the ground wire and impedance happen to resonate for those frequencies.  Once or twice I've inadvertently hooked up my wires incorrectly after having disconnected them for a storm.  I was surprised to get fairly good copy at very low signal levels for some frequencies.  In fact, some of the best copy I've had for Northwoods Radio on 6925 was in 2008 or 2009 when I inadvertently hooked my ground wire to the Hi-Z antenna input.

But most of the online articles I've seen touting the advantages of the "Earth" antenna are based on voodoo, at best.  The colorful Nikola Tesla continues to inspire new generations of true believers who are more interested in his rumored musings on the paranormal and junk science than on anything provable.

Most of those musings on the paranormal and radio seem to date back to the Interweb 1.0 era of the 1990s and early 2000s.  Many of those sites vanished when Geocities, CompuServe and others canceled freebie site hosting.  I used to have several sites bookmarked that emphasized radio related aspects of the paranormal, junk science, etc.  They were damned entertaining reading, a helluva lot more fun than reading most amateur radio hobbyist sites that argue endlessly about the merits of the T2FD and G5RV, or lack thereof.   ::)
That li'l ol' DXer from Texas
Unpleasant Frequencies Crew
Al: Palstar R30C & various antennae
Snoopy: Sony ICF-2010
Roger: Magnavox D2935
(Off-air recordings.)
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Offline The Hokie

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Re: Using the Earth as an Antenna
« Reply #5 on: November 05, 2011, 0348 UTC »
They were damned entertaining reading, a helluva lot more fun than reading most amateur radio hobbyist sites that argue endlessly about the merits of the T2FD and G5RV, or lack thereof.   ::)

I'm a lurker on a few vintage car forums, and not once have I seen someone bemoaning the fact that seatbelts were made mandatory in new cars. But it's fair game in ham radio :D
The machine does not isolate us from the great problems of nature but plunges us more deeply into them. - Antoine de Saint-Exupéry

Offline Pigmeat

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Re: Using the Earth as an Antenna
« Reply #6 on: November 07, 2011, 1338 UTC »
Troops on both sides of the Western Front in WWI used earth antennas for comms between the trenches. You've got to pump quite a bit of power into the ground,but it can be done.

I can imagine soldiers on both sides getting a nasty jolt in those muddy trenches when the CO ordered those spark gap generators fired up for urgent comms.

In the next war,one of the few ways American hams were allowed to operate was through ground antennas. From what I understand,talking to hams from that era,the range was very limited,a half-mile to a mile at best,depending on the soil and water table.

Offline weaksigs

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Re: Using the Earth as an Antenna
« Reply #7 on: November 07, 2011, 1505 UTC »

While living in Vermont I had significant room for antennas and installed
some high, well tuned, wires especially for 40 meters. One of my favorite
activities was listening for DX stations during the “grey line”. However,
even in the Vermont boondocks noise can still be a problem at times. By
accident I discovered that running a length of insulated wire length
directly on the ground, I could often hear signals that were otherwise
buried in the noise. True my “S” meter didn’t go very high as signals were
reduced in amplitude, but noise was reduced at a greater rate, and in
some cases hardly discernible, permitting solid copy at times where the
same signals failed to be heard on a much higher well tuned antenna. I
discovered that an on ground antenna worked even when it was completely
buried in snow. On ground insulated antennas can be a pleasant surprise at
times especially on the “noiser” frequencies typically below 10 Mhz or so.

Its worth trying!

weaksigs

Central Florida
136' random wire for general HF,
Winradio Excalibur G31 & Kenwood TS-590

Peace!

Offline Lex

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Re: Using the Earth as an Antenna
« Reply #8 on: November 07, 2011, 1518 UTC »
...By accident I discovered that running a length of insulated wire length directly on the ground, I could often hear signals that were otherwise buried in the noise.

Ditto.  Occasionally I'll tote a Sony 2010 portable out to the back yard to get away from household RFI.  But it's still fairly noisy because I can't get more than 50 yards away from utility lines in any direction.  I discovered by chance that an external antenna wire stretched out across the ground was much quieter than the same antenna tossed up a nearby tree.  As you've described, signal level is reduced but is much easier to copy due to a more favorable signal to noise ratio.

I've never had a chance to try the BOG (beverage on ground) or snake type antennas, but several folks report good results with them for coping with noisy conditions.
That li'l ol' DXer from Texas
Unpleasant Frequencies Crew
Al: Palstar R30C & various antennae
Snoopy: Sony ICF-2010
Roger: Magnavox D2935
(Off-air recordings.)
Email=my name at hotmail dot com

Offline Pigmeat

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Re: Using the Earth as an Antenna
« Reply #9 on: November 07, 2011, 1853 UTC »
I use the Beverage On Ground system in the summer. Alan Maxwell of KIPM fame put me on to it years ago. For HF,100 feet of wire can be quite effective,but I like 200 plus feet to dig the tougher signals out.

The first time I used it,I was at a farm. Things are electrically quiet out there to begin with. I hooked the BOG to my Sangean 909 and the band went silent. I thought I'd fried the front end of the receiver until I did a bandscan on the 90 meter band. Most of those stations that the Brian Alexander guy logs in the mags and online,actually were there. I was sold. (Forgive me,Brian,for thinking you were full of it.)

It's amazing how just a bit of height can effect the noise levels. During the summer,on the ground,the BOG is very quiet. Raise it to 8-10 inches and the noise begins to become a factor. At a couple of feet the noise overcomes all but the flamethrowers.

Offline Sealord

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Re: Using the Earth as an Antenna
« Reply #10 on: November 07, 2011, 2230 UTC »
Dave Valko used a 315' BOG for most of his europirate catches with good results.

On the underground antenna thang, I always was intrigued by Robert Felix webpage:

http://www.borderlands.com/newstuff/research/FelixRadio/FelixRadio.htm

I don't have a tube rig to try his approach, but it sounds interesting.

North East Florida
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Offline Lex

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Re: Using the Earth as an Antenna
« Reply #11 on: November 08, 2011, 0339 UTC »
http://www.borderlands.com/newstuff/research/FelixRadio/FelixRadio.htm

Hey, that's one of the sites I used to have bookmarked but lost track of.  Thanks for the reminder!
That li'l ol' DXer from Texas
Unpleasant Frequencies Crew
Al: Palstar R30C & various antennae
Snoopy: Sony ICF-2010
Roger: Magnavox D2935
(Off-air recordings.)
Email=my name at hotmail dot com

Offline Pigmeat

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Re: Using the Earth as an Antenna
« Reply #12 on: November 08, 2011, 0414 UTC »
The copper rod antenna pictured there,is very similar to the ones I read about being used in the trenches in WWI.

In both Florida and the Yucatan cave divers are using modified CB radios to communicate with the surface and aid in tracking them. I've seen footage of it in action in the Yucatan. It looks like a Field Day Foxhunt on the surface. They're now experimenting with coil antennas on the receivers up top to increase ground penetration beyond the current 30-40 feet range in depth.

In the Yucatan many of the dive teams are funded by Universities as part of Archeological and Geological research. With even a small amount of grant money,it will be interesting to see how far they can push the communications technology.

Offline paranoid dxer

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Re: Using the Earth as an Antenna
« Reply #13 on: November 08, 2011, 0436 UTC »
     l
     l
     l
     l------------------>
     l         radiator
     l
     l
counterpoise

intersection is feed point    cut for freq of choice   lay it on ground  transmit in direction of arrow
very easy to setup and take up    works well for transmit  ;)
« Last Edit: November 08, 2011, 0438 UTC by paranoid dxer »
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Offline Swede P

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Re: Using the Earth as an Antenna
« Reply #14 on: November 13, 2011, 1659 UTC »
From what I understand,talking to hams from that era,the range was very limited,a half-mile to a mile at best,depending on the soil and water table.

You are quite correct that the idea of passing radio signals through the earth can be done. I have experimented with electronics kits and have done that very thing in the garden, where both TX and RX were connected to separate copper pipes driven a few inches into the soil. However, whether that substantiates the claim that one can connect his receiver to the earth as a way of picking up signals off the air (literally) from shortwave stations around the world and that it works better than an aerial is very much in question.