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Author Topic: Hidden antenna options ?  (Read 40316 times)
VE3FMC
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« Reply #15 on: December 31, 2012, 12:30:09 PM »

Several of us have had very good luck with small transmitting loops.  They do require more careful assembly than other antennas, but properly sized and assembled, the efficiency can be very respectable.

If you want anecdotal evidence, I have worked plenty of DX using small loops (5' diameter or less) on 40m through 6m.  They are fantastic for domestic QSOs.  Others are having similar results for loops that are carefully constructed.

You can hide a small loop anywhere, indoors or outdoors.  Just paint it some really boring color (gray, brown, dark green, etc.) and nobody will even know what it is.  Throw some kind of cover over it and nobody will ever see it.  You can hide it in bushes, or on the back side of a wooden privacy fence.  You can also hide it in an attic or in an out building.  Hang it above the lawn mower in a shed, and it will never be seen.

Great post Matt. Maybe you could give us more details on your small loop antennas you have built over the years. Plans etc to help those out who have antenna restrictions.

Happy New Year
Rick VE3FMC
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K5TED
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Posts: 780




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« Reply #16 on: December 31, 2012, 07:07:37 PM »

SV1ENS -

Look into the SGC auto-couplers. You could work a good portion of the world with just a 6' x 6' 5-turn wire loop on a PVC or lighter weight frame.
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WB2JNA
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« Reply #17 on: January 01, 2013, 10:03:23 AM »

I would jump at the chance to have an attic antenna if the attic is relatively low on metal that could interfere with the antenna. Be careful installing it, but antennas in an attic can work very well and are not subject to the elements and their harsh effects. There are many choices you have but the simplest might be a dipole fed with ladder line and used with an auto tuner or manual tuner at the rig.
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KB3ZBE
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Posts: 19




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« Reply #18 on: January 04, 2013, 10:41:21 PM »

If you have adequate attic space, I highly recommend this as an option in a restricted area
as I live in.  The shingles do not cut down on the signal strength much at all.

I'm fortunate that my roof measures about 46 feet along the peak so I've been able to
install a 10 meter dipole along with a "shorty" G5RV at 45 feet.  There is also a Diamond
discone up there for 2 / 6 meters.

They all work great -- the only issue I have is when the snow depth gets too deep on my
roof (I live in Pittsburgh, PA) it tends to cut down on the signal.  But I have made QSO's
from over 5,000 miles away on USB.

Good luck to you and 73,

Mike
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LA9XNA
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Posts: 110




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« Reply #19 on: January 05, 2013, 05:11:44 AM »

One possibility is to make a loop around your building.
Hang the antenna a of PVC standoffs from the edge of your roof. (I split a 2m folding meter and spraypainted it to match my building)
Feed the antenna with an autotuner/balun combination. Depending on the size of your house you can operate on all bands.
If any of you neighbours complain about the wire tell them that it is a new and experimental electromagnetic non lethal bird repellant to prevent the birds from shitting on your house.
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W4LI
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« Reply #20 on: January 05, 2013, 08:38:36 AM »

I wish you the best.  I've also gone the stealthy antenna route.  None are ideal, but all have kept me on the air.

Three more options include near ground mounted hatted compact vertical dipole, and either a real rain gutter (as I have done) or a disguised rain gutter (plastic gutters with a vertical or dipole concealed inside).  The raingutter uses a handful of radials in the grass and an icom tuner.  The verticals have fixed/switchable tuning networks at the center.

I use the transworld verticals, but you might also make a hatted vertical dipole with wire on your fence.  These have outperformed my gutters, partly because I run 1KW vs 100W, but your mileage may vary.

Best,
Dan, W4LI
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W4LI - Dan Hoogterp
VE3FMC
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« Reply #21 on: January 06, 2013, 05:45:46 AM »

I was in the local Canadian Tire store the other day and walked by a rack with MIG welding wire in it. Both copper and aluminum were in small spools, 2 lbs a spool. That wire looks interesting for low profile antennas. Not sure how strong it is but for $10/spool I am going to find out.

It would be ideal for attic antennas where weather is not a factor.
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WB6BYU
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Posts: 13479




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« Reply #22 on: January 06, 2013, 10:19:33 AM »

Quote from: VE3FMC

I was in the local Canadian Tire store the other day and walked by a rack with MIG welding wire in it. Both copper and aluminum were in small spools, 2 lbs a spool...



The copper-coated welding wire is NOT a good choice for antennas, at least if they are
going to be outdoors.  The copper coating is VERY thin, and the underlying steel is more
lossy than other options.  A friend put up a long wire antenna using some that worked
great for one day:  by the next morning the fog had corroded the copper off in places.
I've had the same problem using copper-coated welding rod for 2m whips, which quickly
became radiating dummy loads.

For indoor use, standard insulated copper hookup wire works fine. 
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VE3FMC
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« Reply #23 on: January 07, 2013, 05:58:43 AM »

Quote from: VE3FMC

I was in the local Canadian Tire store the other day and walked by a rack with MIG welding wire in it. Both copper and aluminum were in small spools, 2 lbs a spool...



The copper-coated welding wire is NOT a good choice for antennas, at least if they are
going to be outdoors.  The copper coating is VERY thin, and the underlying steel is more
lossy than other options.  A friend put up a long wire antenna using some that worked
great for one day:  by the next morning the fog had corroded the copper off in places.
I've had the same problem using copper-coated welding rod for 2m whips, which quickly
became radiating dummy loads.

For indoor use, standard insulated copper hookup wire works fine.  

If that is the case why is all of the antenna wire listed at Wireman copper coated steel wire? Yes the copper coating may be thicker, that could be the only difference.

For the cost of $10 I will buy a spool, cut a piece of it off and hang it outside and see what happens.

« Last Edit: January 07, 2013, 06:01:01 AM by VE3FMC » Logged
VE3FMC
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« Reply #24 on: January 07, 2013, 01:34:50 PM »

I checked that MIG wire out again today. It comes in 3 sizes, .25, .30 & .35. However I think it could be a PITA as it seems to quite stiff. So much for cheap invisible antenna wire.
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AB9TA
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Posts: 20




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« Reply #25 on: January 09, 2013, 09:13:23 AM »

Could you put up a birdhouse? When I lived in a rental house, I got permission to put up a birdhouse on a 10' copper pole, I installed it on a wooden stockade fence. Amazingly enough, it was also usable as an antenna!
The corner of the fence was next to the house, and I ran the RG-8X under some existing mulch, attached a couple of radial wires to the bottom of the fence and off we went. It worked 6 - 20M very well, and was usable on 30M.
As a novice I installed a dipole in the attic of my apartment building using 50' of wire on each leg. I zig-zagged the wire to make it fit and fed it with RG-58. It worked better than the aluminium gutters. Used it on 10-80M

I'm curious as to why radials can't be used in your backyard, is it a communal area? If not, you could just lay radials on the ground and stick them down with lawn staples. After a while the grass will grow over them.. I use thin stranded insulated wire in black, dark gray, or brown, it's practically invisible in the grass to start off. Stranded works better as solid wire will take a shape and may stick up to be snagged by a foot or a lawn mower.. Also, be careful with your weed-whacker near the radials..

When I was renting, I always got a kick out of trying to set up a stealth antenna..  Not only do you have to hide the antenna, you have to work on it in such a way that your neighbors don't catch on to what you're doing..  In a way, kinda like the old black & white movies where the characters used secret radios..

Hope to see you on the air,
73!
Bill AB9TA
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SV1ENS
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Posts: 124


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« Reply #26 on: January 09, 2013, 09:19:22 AM »

I got a spool of .64mm welding copper wire from CT, it is a bit stiff, but it should be ok for a 15x18 foot loop. As for corroding, if it stays up for one winter, I'll be happy :-)

Besides, I expect to do a lot of shape and size experimenting. Once I get the results I want, I'll look for varnished transformer copper wire which will last much longer...

Only thing I need now is to find spacers to keep the wire away from the fence, and a way to bring the coax into the basement...

73
Demetre VE3/SV1ENS
« Last Edit: January 09, 2013, 09:30:09 AM by SV1ENS » Logged
SV1ENS
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Posts: 124


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« Reply #27 on: January 09, 2013, 09:29:43 AM »

The birdhouse I've considered, just like a flagpole, I'll actually try getting approval for
both, however they need to be free standing, nothing can be mounted on the fences which are considered common area fixtures. The backyard although private, is considered common area, installing underground radials is an issue...

73
Demetre - VE3/SV1ENS

Could you put up a birdhouse? When I lived in a rental house, I got permission to put up a birdhouse on a 10' copper pole, I installed it on a wooden stockade fence. Amazingly enough, it was also usable as an antenna!
The corner of the fence was next to the house, and I ran the RG-8X under some existing mulch, attached a couple of radial wires to the bottom of the fence and off we went. It worked 6 - 20M very well, and was usable on 30M.
As a novice I installed a dipole in the attic of my apartment building using 50' of wire on each leg. I zig-zagged the wire to make it fit and fed it with RG-58. It worked better than the aluminium gutters. Used it on 10-80M

I'm curious as to why radials can't be used in your backyard, is it a communal area? If not, you could just lay radials on the ground and stick them down with lawn staples. After a while the grass will grow over them.. I use thin stranded insulated wire in black, dark gray, or brown, it's practically invisible in the grass to start off. Stranded works better as solid wire will take a shape and may stick up to be snagged by a foot or a lawn mower.. Also, be careful with your weed-whacker near the radials..

When I was renting, I always got a kick out of trying to set up a stealth antenna..  Not only do you have to hide the antenna, you have to work on it in such a way that your neighbors don't catch on to what you're doing..  In a way, kinda like the old black & white movies where the characters used secret radios..

Hope to see you on the air,
73!
Bill AB9TA
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N8YQX
Member

Posts: 79




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« Reply #28 on: January 09, 2013, 11:52:35 AM »

Demetre,

How about a grass antenna?  Low cost, very low visibility, and somewhat directional.
I have talked with someone who tried this, but I have not had the chance to actually use it.  So YMMV.

http://www.radiosurvivalist.com/antennas/stealth-hidden-camouflage.asp


N8YQX
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73,
N8YQX
WB6BYU
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Posts: 13479




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« Reply #29 on: January 09, 2013, 12:39:09 PM »

Quote from: VE3FMC

If that is the case why is all of the antenna wire listed at Wireman copper coated steel wire? Yes the copper coating may be thicker, that could be the only difference.



True CopperClad(R) wire as is used for antennas is 30% copper.  MIG may be
about 0.05% to 0.30% copper by weight (thinner gives better results.)  So there
is a difference of 100 : 1 or more in the coating thickness.

For a 1mm wire, the thickness would be about 60um for copper clad vs. 0.6um
maximum for copper plated (and perhaps 0.1 microns for the better quality
MIG wire - that's 1000 Angstroms, or roughly 400 atoms thick.)


Another important difference is the skin depth at the frequency of operation.
The types of 450 ohm twinlead using CopperClad(r) wire have higher losses on
160m than regular copper because the copper isn't thick enough to keep the
RF currents out of the lossier steel core.  (Magnetic materials have hysteresis
losses at RF because the magnetic field can't switch as fast.)  A thinner copper
coating will have higher losses, especially at higher frequencies where the
depth of the copper is no longer less than the skin depth.


Not that you can't try it out if you already have the wire - it may still work.
But even in a sheltered location I would expect the losses to be higher for
the MIG wire due to the skin depth. This particularly becomes an issue when
antennas are smaller than full-sized, because of the increased currents.
Your 15' x 18' loop may be OK on 20m and higher frequencies, but pressing
it into service on 40m will cause high currents and I think the losses will
increase significantly.

But try it and see.
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