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Author Topic: underground antenna project  (Read 8830 times)
KD8CEQ
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Posts: 4




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« on: November 04, 2006, 12:13:12 AM »

I have a question regarding underground antennas  i am doing some research at present  on these and found a paper on research and design of undrground antennas by james rodgers his design was used by the u.s navy  for long range communications during wwII  i am planning to construct one using a standard dipole design enclosed in 3/4 in pvc and using twin lead for feed line also in pvc pipe back to the shack
all  buried about 3 ft in the ground
with a stubb out for the feedline
to go thru does anyone have any info on this design or could give me some design suggestions \\\\  if so please contact me via email  amradioguy@yahoo.com by the way  two reasons i am considering this for the experiment and the ccrs/xyl

73s
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WD8CRT
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Posts: 26


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« Reply #1 on: November 04, 2006, 07:51:51 AM »

This antenna will work great for you if you use a counterpoise wire as high in the air as possible.  Save yourself the digging and use a "grasswire" antenna, also with an aerial counterpoise.

Underground antenna?  Great for working someone a few miles away or submarines.

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WD8PTB
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Posts: 670




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« Reply #2 on: November 05, 2006, 04:34:44 AM »

Almost all "dirt" will absorb RF energy in the ham bands. Some people burry the electrical power to their house to minimize noise.  Don WD8PTB
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W5ONV
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Posts: 0




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« Reply #3 on: November 05, 2006, 06:57:49 AM »

 Multiple postings causes me to have diarrhea for 8 to 10 hours !!
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N2AXZ
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Posts: 90




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« Reply #4 on: November 06, 2006, 07:37:59 PM »

I worked in the submarine communications community for the US Navy for 10 years, spending LOTS of time working (and playing!) with VLF, LF, and ELF antennas.  My question to you first is "Why are you building an underground antenna?"  WHat is it you are trying to receive?  At HF, such antennas will perform extremely poorly because of the losses in the ground.  Using buried  antennas is sometimes used for receiving signals at ELF, partly because it is a good way to get a nice quiet location away from other sources of interference.  The ELF antennas that the Navy used in WIsconsin and Michigan were actually loops --- center-fed dipoles that were grounded at the ends (about 15 miles apart), and the low ground conductivity made the effective loop area formed by the current flow in the ground quite large.  These transmitters operated on a frequency of 76 Hz (yes -- Hz!) and had an extremely low efficiency.  The transmitters were just Class D amplifiers that pumped about 1.5MW into the antenna, resulting in a whopping 1 watt radiated!

Hope this helps,

David, N2AXZ
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N0RIE
Member

Posts: 7




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« Reply #5 on: April 19, 2011, 07:55:34 AM »

well i use an underground ant, and i get sigles from all over and get good reports on it.5/8to 10/over 40 at times ..the one i use is 135ft. each leg feed with a 4:1 balun 25 ft coax comming to tuner i work all bands with it...most of the reports i get are in 5/8to 5/9
thanks gene
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K7MDO
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Posts: 325




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« Reply #6 on: April 19, 2011, 08:12:54 AM »

I wonder if the government might have been able to balance the budget selling the worms they drove out of the ground with 1.5 Megawatts?
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KG6MZS
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Posts: 476




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« Reply #7 on: April 19, 2011, 09:29:08 AM »

This antenna will work great for you if you use a counterpoise wire as high in the air as possible.

um, [scratches head] then wouldn't the "counterpoise" become the....   oh, never mind ;-)
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N6AJR
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Posts: 9921




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« Reply #8 on: April 19, 2011, 10:20:16 AM »

as an Old Hippie from the 60's I can't pass this  up,




Underground Antennas, Can You DIG it.........  Smiley
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WB6BYU
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Posts: 13461




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« Reply #9 on: April 19, 2011, 03:30:06 PM »

Actually such antennas ARE used.  I've seen some articles (even in ham publications other than the April
issue) and some professional literature.  Some suggestions;

1) don't bury it any deeper than necessary.  A few inches is better than a few feet (besides being easier
to dig.)  Dirt isn't a good RF propagation medium.

2) Use as large of a pipe as possible.  Suspend the wire inside it using Styrofoam or some other good
insulator to reduce earth losses.  The same goes for the feedline - the twinlead will induce currents in
the dirt if it isn't spaced far enough.  I'd aim for a minimum spacing of several times the spacing between
the conductors.  (A shielded line such as coax might have lower losses, at least in some
conditions, as it reduces the currents induced in the dirt.)

3) The antenna won't be resonant at the normal length due to the dielectric loading of the dirt.  Expect
it to be shorter - the exact amount depends on the size of the pipe and other factors, but it could be
as much as 1/3 shorter than a standard dipole in air.
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K4SAV
Member

Posts: 1850




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« Reply #10 on: April 19, 2011, 05:22:49 PM »

well i use an underground ant, and i get sigles from all over and get good reports on it.5/8to 10/over 40 at times ..the one i use is 135ft. each leg feed with a 4:1 balun 25 ft coax comming to tuner i work all bands with it...most of the reports i get are in 5/8to 5/9
thanks gene

Assuming "underground" is used in the sense of "under the dirt" how about giving us some more details on your antenna.  How deep is it buried?  Is that a current mode balun?  Which direction is the impedance transformation, step up, or step down, to the coax.  Is it a commercial balun or homebrew?

I have often thought of trying an underground Beverage (just barely below the grass), for receiving only.  I know the gain will be very low but gain is not a requirement for a receiving antenna.  I am curious as to how it would perform.  I may yet try that experiment when I have some spare time.

Jerry, K4SAV
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AA4HA
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Posts: 1581




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« Reply #11 on: April 20, 2011, 08:12:47 AM »

I wonder if the government might have been able to balance the budget selling the worms they drove out of the ground with 1.5 Megawatts?

They do, did you ever hear of the "school lunch program"?

Tisha, AA4HA
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
N3JBH
Member

Posts: 2358




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« Reply #12 on: April 20, 2011, 08:31:25 AM »

I wonder if the government might have been able to balance the budget selling the worms they drove out of the ground with 1.5 Megawatts?

They do, did you ever hear of the "school lunch program"?

Tisha, AA4HA

That was a great one Tisha  Grin
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K8AXW
Member

Posts: 3958




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« Reply #13 on: April 21, 2011, 09:44:01 PM »

I'm more interested in learning what a "CCRS/XYL" is.  I know what an XYL is....but what is a CCRS?  If it's what I think it could be, maybe the answer is to bury her underground!  ;-)

I mean, I've been reading post after post from guys who have antenna restrictions initiated by their wives but this one take the cake!  Save yourself a lot of grief and just run your RF to a good ground rod.

BTW, I understand the 1Mw ELF transmitter in Michigan really created a problem with the cattle and RF on the fences!
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NA0AA
Member

Posts: 1042




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« Reply #14 on: April 22, 2011, 10:46:35 AM »

I'm more interested in learning what a "CCRS/XYL" is.  I know what an XYL is....but what is a CCRS?  If it's what I think it could be, maybe the answer is to bury her underground!  ;-)

It's CC+R's, which stands for Conditions, Covenants and Restrictions.  AKA, the Homeowner Associations "Rule Book".  Depending on your HOA, your CC+R's might govern:

What you can park in front of your house
How long you can leave your garage door open [no kidding]
what colors you can paint your house
what plants you can use in your yard
how often you mow your lawn
what you can put up in your back yard
what kind of flagpole you can have

and etc. and etc.

Sadly, the CC+R comes about as the local Gov't tries to cut their operating expenses, they use HOA's instead of having a real gov't in the area.  They suck, but I have a friend who is constantly telling me how much he loves his house, because of their STRICT HOA: when the neighbor parked an old car on the street, he got to make a phone call and it goes away.  Yea, he's a piece of work.  And there is not one personality in his entire subdivision, in fact, I'm not sure their is any brain activity of any sort.  The only Amateur that was there has moved.  He was right next door.
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