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eHam Forums => Antenna Restrictions => Topic started by: SV1ENS on December 28, 2012, 08:33:58 AM



Title: Hidden antenna options ?
Post by: SV1ENS on December 28, 2012, 08:33:58 AM
Hello all and Merry Christmas,

Just completed a move to a new house in an area where antenna restrictions are not only strict, but they are also enforced...    :-[ :-[

My new home is a townhouse just north of Toronto in Thornhill, a community with low buildings and a relative elevation compared to the GTA, hence the "hill" in it's name. Our front side has an excellent unobstructed southern exposure and the back side (northern) has a nice back yard but with the back of another house near when the yard ends, but with a relatively nice opening with a east/west opening.

After giving this a great deal of thought, and having discussed this with locals who did not approve of any kind of antenna, not even a window mounted one, I concluded that a hidden antenna is my only option.

Option 1: Magnetic loop or bend dipole installed in the free space of the garage roof/attic (south side)

Option 2: Vertical end fed folded dipole disguised as a small free standing flag pole installed at the back yard (radials not possible).

Option 3: A horizontal wire loop mounted on the back yard wooden fence, about 6 feet from the ground, or some sort of zig-zag pattern from fence side to side.

Option 4: Any kind of free standing antenna structure as long as it is under the back yard fence line...

I'm leaning towards the back yard, using the fence as an installation structure for a wire antenna, because construction will be easier and getting the feeding cable into the house is easier...

I welcome any thoughts or tips !

73
Demetre - VE3/SV1ENS
 


Title: RE: Hidden antenna options ?
Post by: AC4RD on December 28, 2012, 09:16:18 AM
I've used horizontal loops a lot over the years, and I've always been satisfied with them.  Never quite as low as 6 feet (shouldn't you be saying 1.9meters?)  ;)  but I'm sure it would work.  One potential benefit to the fence-loop: if you feed it with twinlead from a tuner, you can use it easily on all bands, or darned near all, depending on how much fenceline you have to work with.   Good luck!


Title: RE: Hidden antenna options ?
Post by: VE3FMC on December 28, 2012, 10:29:55 AM
So many options but not a lot of good options.

Now let me say I have a friend who lives in IN. His yard has no trees, he has no tower, but he does have a 7 foot wood fence around his back yard.

He has a G5RV installed along the top edge of that fence. I am not exactly sure what he does with the twin lead feed line but I can find out if you want me too.

He only runs 100 watts. But he manages to work DX with that setup on CW and by using the digital modes. He never operates SSB.

Not the ideal antenna setup for sure, but he is on the air and making contacts and having fun while doing so.

Maybe you can string up a wire just above the top edge of the fence. Use small magnet wire so it will be nearly invisible. Feed it with 300 ohm ladder line, which is small in size.

Or put the mag loop in the garage attic, or better yet mount it outside as it will be below the fence line and out of sight of neighbours.

Good luck, let us know how you make out. And if you are new to Ontario welcome to the province!

73, Rick VE3FMC


Title: RE: Hidden antenna options ?
Post by: K5LXP on December 28, 2012, 11:08:38 AM
I would try all the above.  None of these options are good but when you're dealing with severe restrictions you want as many options as you can get.   Get a coax switch, a good tuner and pick the antenna that works the best for whatever band you're on.  I wouldn't limit myself to just one antenna.

Mark K5LXP
Albuquerque, NM


Title: RE: Hidden antenna options ?
Post by: K3ANG on December 28, 2012, 09:11:08 PM
Another option is to erect a portable antenna when the opportunity exists.
I would use a 3-way mount ((For illustration only): http://www.radioshack.com/product/index.jsp?productId=3088301)
with a CGT-144 with 2 matching radials for 10 meters on my deck. 
I would take it down when I was finished.
You can also use the same mount with quarter wave lengths of wire cut to frequency.
After mounting the 3-way on the ground and a reasonable distance from the house,
attach the 3 wires, (radials and radiator) getting the radiator as high off the ground
as you can get it, even if you have to have it sloping.
If you don't have trees, mount the free end to your highest window in the back.
You're gonna need a bolt to match the threads of the antenna portion of the mount
and I've found them at any hardware store. 
Or, you can do the reverse, as this URL shows (for illustration only)
http://www.qsl.net/wb3gck/2ndstory.htm

GL & 73.
Where there's a will, there's a way.
Greg, K3ANG 


Title: RE: Hidden antenna options ?
Post by: KH6AQ on December 29, 2012, 06:31:19 AM
What bands do you want to work?


Title: RE: Hidden antenna options ?
Post by: KA4NMA on December 29, 2012, 05:54:25 PM
What about a flagpole with vertical wires for each band? I have seen this in some ARRL books.  Or how about a flagpole with a vertical wire being feed to an auto tuner (SGC, ETC)? The tuner could be hidden in a waterproof box and flowers planted to hide it.  In either case, bury as many radials if you can.  Even short radials would be better then none.  Another option is a random loop/wie attached around the eaves of your house.   This is the option I am going to try.

Randy ka4nma


Title: RE: Hidden antenna options ?
Post by: SV1ENS on December 29, 2012, 09:13:31 PM
Thanks to all for the reply...

AC4RD:
I also like loops, low noise, multiband (with a tuner), and easy to make. As for metric, although Canada is metric, realstate measurements have managed to resist and are still in imperial :-)

VE3FMC:
Thanks for the welcome, however I've been an Ontario resident since the 70's, just never got around to a Canadian call... A G5RV would actually be a good choice, but unfortunately a center fed dipole is not easy to conceal. A wire running the fence is most probably the way to go, hopefully it won't zap the squirrels who use the fence as a pathway :-)

K5LXP:
Will do just that, try different wire configurations till I find the one that works best for me.

K3ANG:
I'm currently using a 40m buddypole dipole, however it's not practical taking it down everytime I go QRP, especially during winter.

WX7G:
Mainly 40m and 20m digi.

KA4NMA:
A flagpole is an option, my neighbours are resistive to the idea, I have played the patriotism card and they did ease down a bit, but it's still a little dodgy.

Summing up:
It is unfortunate but antenna restrictions are very much a reality in my area, and the only way I can get on the air is a concealed antenna.
My small back yard can conceal an irregular shape loop and/or an end fed antenna, or some form of clothesline antenna, also considering a rotary clothsline antenna (something like this:  http://www.smalltownvegan.com/wp-content/uploads/2012/05/clClothesLine1.jpg (http://www.smalltownvegan.com/wp-content/uploads/2012/05/clClothesLine1.jpg)) I'm sure I've seen one somewhere... Will give them all a try and see what works :-)

73
Demetre - VE3/SV1ENS


Title: RE: Hidden antenna options ?
Post by: VE3FMC on December 30, 2012, 07:05:42 AM
Demetre don't worry about the damn squirrels! If you kill one, another one will replace it  ;D

I like the suggestion that you put up a couple of antennas. If you can build a mag loop for the garage attic that gives you one option.
Then run the wire along the fence line. Or just above it, use small wire and some PVC pipe for supports.

Here is a design for a mag loop built without the expensive vacuum variable capacitor. I am going to build one of these in the new year. It will give me something to do as I am retired and winter days are long and boring for me (No golf  :( )

http://www.standpipe.com/w2bri/build.htm


Title: RE: Hidden antenna options ?
Post by: K3ANG on December 30, 2012, 01:31:20 PM
Here's some inspiration that has worked for one ham:
http://www.qsl.net/g0kya/multibanddipole.pdf

IMO, I can see you building multiple antenna systems,
one  internal (the garage roof), the other external (on the fence).

Good luck with your endeavour.
Greg, K3ANG


Title: RE: Hidden antenna options ?
Post by: WD4ELG on December 30, 2012, 08:12:26 PM
QST has a wealth of articles.  You could do a base fed vertical wire that is very thin, some radials.

Even better, use an antenna that can be put up and taken down quickly:

http://www.twantennas.com/products/index.html

Buddipole

MP-1 vertical http://newsuperantenna.com/MP1-SuperStick-Portable-Vertical-Antenna-Deluxe/

http://www.g4ilo.com/stealth.html

Or attic antenna: http://www.arrl.org/indoor-antennas

Keep us posted; it does not take much to make digital QSO's...even DX!


Title: RE: Hidden antenna options ?
Post by: VE3FMC on December 31, 2012, 03:56:08 AM
A friend of mine operates a Screwdriver antenna at home using one long radial wire. Works well for him. http://www.ve3edy.com/


Title: RE: Hidden antenna options ?
Post by: AB1XG on December 31, 2012, 07:14:21 AM
I'm in the same situation, have been since November 2010.

Some of my antennas have been a 31 foot 10-40 meters S9v vertical (now available from LDG) hidden in the woods behind my house and a 124 foot log wire antenna (10 meters-160 meters) also hidden in the woods behind my house.

That all works fine if you have woods handy and nearby. But in my case it demanded 135 feet of coax buried in my back yard in order to reach the woods .... Plus winds have brought a few treetops down and taken parts of my log wire to the ground.

I want to get rid of the long buried coax run and get as many antennas as possible in or on my house. So I built a 6-20 meter Carolina Windom and hung it from the rafters in my two car garage. I was really amazed at how well this antenna performed so I added length to it to add 30 and 40 meters. While it worked at approximately 10-12 feet off the ground, it was not very satisfactory on 30 or 40 meters. But I did add a 6 meter stub (like a fan dipole, only Carolina Windom style) to it so it's resonant on 6 meters. Though horizontally polarized (mostly) I can easily hit my local 6 meter repeater that's about 10 miles away.

The pitch of my garage's roof is a bit shallow so there's not much room from the rafters to the inside of the roof above them but I'm confident I can attach a small Radio Shack TV rotor to one of the rafters and put a 6 meter Moxon on it.

I run mostly digital modes, around 99% of my QSO's are JT65. There are JT65 frequencies on each band so I mostly go to that frequency and stay there until I change bands. My 30 meter and lower antenna plans include a possible MFJ Magnetic loop, from what I read they're a suprizingly effective antenna but if you move even slightly from your operating frequency you have to retune. Not a problem if you run mostly digital modes such as JT65, JT9 or PSK, etc.

I've been looking longingly at my downspout (rain gutter). I live in a single story house, what I want to do would work much better on a two story house. But I already have everything I need so it will only cost a bit of time to setup.

My house is pre-fab, it has skirting and sits on a slab. So I can easily run a short coax run to one of those MFJ weather proof remote tuners. I can connect the hot lead to the down spout and the ground to my radial field. Because it's winter the radials will quickly be buried in the snow.

My down spout is 10-12 feet vertical to the edge of the roof, then it runs continuously (horizontal) along the edge of my roof for about 60 feet to the other down spout (10-12 feet again) at the other corner of the house. Again, it's a bit low with my single story house so I'm not sure how well it will work. All I need to do is spend an hour or so to find out ...

There are plenty of options, you can stay within your HOA's rules and still be active.

David N1ZHE


Title: RE: Hidden antenna options ?
Post by: AA5JR on December 31, 2012, 08:10:09 AM
(This is all in the past couple of weeks and this is my first ever setup)

I just recently put up an '80 meter' loop, about 266 feet long.

It is invisible.

It is tucked under the shingles of my house.  My roof is new composition shingles, and they bend up easily.

My friend and I ran it around the whole perimeter of the roof in an hour.

I used 14g stranded insulated wire which I bought at Lowe's in a 500 foot roll.

The end comes back to the beginning, thus a loop.  I connected it to the feedline (regular TV twinlead, 10 feet) which goes through the house wall via a previously-existing cable TV hole in the wall.

I had also just built a '4:1' balun and tried it with the loop first.  My Elecraft K2 internal antenna tuner was able to find a fairly easy match on most bands.

Then I tried it without the balun and it matched up easily on all bands but 160 meters, where it matches but with a higher SWR.


I am a brand new ham, so take all this as such.

I am using the Elecraft K2 (max 15 watts).

I am making daily contacts on 20 meters all around North America, over 1500 miles.

I have talked regionally on 40 meters and 80 meters, out several hundred miles.

I talked to someone on 17 meters yesterday.


I am just starting out and I am amazed how well this is working.



So, just try something out!!!

John
73

(BTW, I don't have any antenna restrictions where I live.  I just wanted to try this as a first antenna/backup antenna/super easy antenna/"All band" antenna)


Title: RE: Hidden antenna options ?
Post by: KK5JY on December 31, 2012, 11:55:18 AM
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.


Title: RE: Hidden antenna options ?
Post by: VE3FMC 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


Title: RE: Hidden antenna options ?
Post by: K5TED 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.


Title: RE: Hidden antenna options ?
Post by: WB2JNA 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.


Title: RE: Hidden antenna options ?
Post by: KB3ZBE 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


Title: RE: Hidden antenna options ?
Post by: LA9XNA 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.


Title: RE: Hidden antenna options ?
Post by: W4LI 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


Title: RE: Hidden antenna options ?
Post by: VE3FMC 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.


Title: RE: Hidden antenna options ?
Post by: WB6BYU 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. 


Title: RE: Hidden antenna options ?
Post by: VE3FMC 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.



Title: RE: Hidden antenna options ?
Post by: VE3FMC 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.


Title: RE: Hidden antenna options ?
Post by: AB9TA 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


Title: RE: Hidden antenna options ?
Post by: SV1ENS 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


Title: RE: Hidden antenna options ?
Post by: SV1ENS 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


Title: RE: Hidden antenna options ?
Post by: N8YQX 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 (http://www.radiosurvivalist.com/antennas/stealth-hidden-camouflage.asp)


N8YQX


Title: RE: Hidden antenna options ?
Post by: WB6BYU 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.


Title: RE: Hidden antenna options ?
Post by: VE3FMC on January 09, 2013, 04:47:32 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.

Thanks for the information Dale.


Title: RE: Hidden antenna options ?
Post by: SV1ENS on January 09, 2013, 06:06:01 PM
Back to the store the wire goes, it's a good thing returning stuff in Canada is really easy...

Anyway, I located proper antenna copper wire, a little expensive, but real copper :-)

Thanks for the info

73
Demetre - VE3/SV1ENS

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.


Title: RE: Hidden antenna options ?
Post by: WB2RCB on January 10, 2013, 05:07:29 AM
I recently installed a High-Sierra HS-1500 Screwdriver in the crawl space of our condo here in Ft. Myers Florida. Added 3 quarter wave radials each for 40, 15 & 10 meters. While not a directional antenna, I have worked many European and stateside stations with great success on 10 & 15 meters.

The antenna itself fully extended with a 6 ft whip is 10.5 feet in length. You can see the installation at my website (www.wb2rcb.com) Use the 1965-2012 tab at the bottom of the page and scroll to the bottom.

Using a system such as this, you should have a fairly efficient antenna on 40 thru 10 meters.


Title: RE: Hidden antenna options ?
Post by: WD4ELG on January 10, 2013, 09:33:22 AM
WB2RCB, that's awesome.  I was looking for some ideas if we get a condo.  (And we were just in Fort Myers this past weekend, what a wonderful couple of days of weather!)


Title: RE: Hidden antenna options ?
Post by: ONAIR on January 11, 2013, 08:21:54 PM
WB2RCB, great antenna setup for a condo!  Your web page was a wonderful half century time machine into the past.


Title: RE: Hidden antenna options ?
Post by: SV1ENS on January 14, 2013, 02:06:17 PM
While having decided to go with a horizontal loop once I get the chance to work outdoors (the wet weather and the local electric company working to fix a cable problem In my back yard has delayed my plans considerably), I came up with this interesting project:

http://www.zerobeat.net/g3ycc/squalo.htm

Although the loop being a much superior antenna to the dipole, I'll give this one a try also, just so I can have a comparison data...

BTW How far apart would be good to keep the two antenna wires if they are to share the same fence area ??

73
Demetre - VE3/SV1ENS


Title: RE: Hidden antenna options ?
Post by: WB6BYU on January 24, 2013, 10:47:57 AM
That's the same principle as the Cobweb antenna:  a half wave dipole bent into
a square.  Feedpoint impedance is low, typically about 12 ohms, so the antenna
is often fed using a step-down transformer or by using a folded dipole for the
elements.

Here is one description of a multi-band design:
http://www.karinya.net/g3txq/cobweb/

Of course, the open half wave loop is just a full wave loop for twice the frequency
open at the far end, so if you put up a 40m loop you can remove a jumper at the
far end to make a half wave loop for 80m.  Because of the high voltage I wouldn't
use an ordinary switch at that point, but a couple feet of wire with banana plugs
or Anderson connectors should do the job, while allowing separate adjustment of
the wire length on both bands.

The performance is the same if you don't open the far end, because the geometry
is the same.  That puts the high impedance at the feedpoint, which can be difficult
to match in some cases, but might be easier if you can't reach the far corner
to open/short the wire when changing bands.

Because of the low impedance due to folding the antenna, ground losses are probably
going to be higher when the antenna is mounted at low heights than with a straight
dipole or a full wave loop.  I'll have to model it to quantify the difference.


Title: RE: Hidden antenna options ?
Post by: KB2FCV on January 24, 2013, 01:36:44 PM
I would try the flagpole antenna and the outside look/dipole on the fence. You may find one may work better than the other depending on what band. I would save the indoor antenna as a last resort. Certainly explore the outdoor options first.


Title: RE: Hidden antenna options ?
Post by: WA6MJE on January 31, 2013, 08:51:47 PM
I recently installed a High-Sierra HS-1500 Screwdriver in the crawl space of our condo here in Ft. Myers Florida. Added 3 quarter wave radials each for 40, 15 & 10 meters. While not a directional antenna, I have worked many European and stateside stations with great success on 10 & 15 meters.
I have also had great luck with a vertical screwdriver and elevated quarter wave radials either in my attic, or outside temporarily elevated at about six feet. A short vertical has very limited bandwidth, and the screwdriver allows me to adjust the antenna remotely to overcome this. I have tried many tricks to push the most out of it I can.  Actually I cut the radials to slightly less than quarter wave so that when I adjust the screwdriver, I am actually Off Center Fed (OCF) which helps match the impedance which starts off lower than 50 ohms at the center. Playing with the size of the radials slightly off of quarter wave can feed the antenna a point closer to 50 ohms, so I avoid a tuner. Check out the Hi-Q brand of screwdrivers as you may find their refinements make incremental differences in efficiency such as a Hi-Q coil. The bigger diameter of the coil is more efficient.  Having the coil higher than the bottom, (i.e. center fed) is more efficient than having it right at the bottom. Also the longer the whip the more efficient.  I have an 8.5 foot stainless whip at the minimum, and using Buddipole parts, I can add sections and have had as much as a 16 foot whip when I used it outside. Putting one section below the coil is one way of improving the location of the coil more toward the center. On lower bands experiment with a capacitive hat one or two feet above the coil. Hi-Q sells them, they look like stainless steel egg beaters. Capacitance to a short antenna adds efficiency.  In essence, the longest whip you can get away with, adding capacitance, using a Hi-Q coil that is 5" in diameter, placing the coil above the bottom feed point and elevated resonant radials will do the trick. These refinements add a small amount of efficiency, which then can make a difference in a needed contact that is marginal. Using these methods I am making the best out of a compromised situation, and have worked all over the world with it.  No one has ever seen it in my yard, or in my attic.

Rene - WA6MJE


Title: RE: Hidden antenna options ?
Post by: SV1ENS on February 15, 2013, 05:38:36 AM
Back to the drawing board...  

A full 20meter loop was installed around the perimeter of my back yard fence, roughly 6 feet from the ground, a 4:1 ballon was used to bring the antenna in the house via RG8x coax. All was well until a chipmunk decided to have a
taste of the copper wire !!

A new chipmunk safe antenna design is required !

73
Demetre - VE3/SV1ENS


Title: RE: Hidden antenna options ?
Post by: K1WJ on February 15, 2013, 07:02:02 AM
Try a MFJ-1979 17ft telescoping whip. Can adjust for 6m to 20m. A true 1/4 wave on band set up for. Retracts to two feet when not in use. Mine is set up at 17ft for 20m with a single elevated radial also cut 1/4 wave 20m, 4 feet off the ground. Works well.
Can see pics on QRZ under K1WJ, will also see 2m/440 Camo Ivy top j-pole, Vertical base in bucket with cement - wood dowel - Have 8 ferrite beads at antenna feedpoint.
Better than Buddi-this & Trans-that-,Screw-this,Trap-that.......
73 K1WJ David - (HOA COVERT OPS EXPERT) ;D


Title: RE: Hidden antenna options ?
Post by: WB6BYU on February 15, 2013, 08:49:07 AM
Quote from: SV1ENS

A full 20meter loop was installed around the perimeter of my back yard fence, roughly 6 feet from the ground, a 4:1 ballon was used to bring the antenna in the house via RG8x coax. All was well until a chipmunk decided to have a
taste of the copper wire !!



We're in the process of moving into a new house, and that is what I'm
considering for my first HF antenna:  a 40m loop around the eaves of the
house, possibly extended to 80m running along the wood fence.

But the neighbor feeds the local squirrels on top of the fence, so I'm
considering ways to discourage them.  Running the coax in flexible
electrical conduit would work, of course, but I'm also looking at
coatings for cables that will discourage them.  An ultrasonic rodent
repeller or recorded raptor cries are other possibilities.


Title: RE: Hidden antenna options ?
Post by: SV1ENS on February 15, 2013, 11:48:19 AM
Ultrasonic pest repellers don't work, it's annoying to the them until they get used to it, and then back they come...

Untreated plastic is a delicacy to rodents, they will get though it eventually. Back when I was building a fiberoptic based wan for a University, the only thing that kept mice/rats away from the cables was a biter tasting gel that was added between the outside jacket and an internal armour, a little messy during termination, but really affective !

What were you thinking of using to coat the cables with ?

73



We're in the process of moving into a new house, and that is what I'm
considering for my first HF antenna:  a 40m loop around the eaves of the
house, possibly extended to 80m running along the wood fence.

But the neighbor feeds the local squirrels on top of the fence, so I'm
considering ways to discourage them.  Running the coax in flexible
electrical conduit would work, of course, but I'm also looking at
coatings for cables that will discourage them.  An ultrasonic rodent
repeller or recorded raptor cries are other possibilities.


Title: RE: Hidden antenna options ?
Post by: K1WJ on February 15, 2013, 11:58:52 AM
How about coating the cables with Rat Poison......73 K1WJ


Title: RE: Hidden antenna options ?
Post by: SV1ENS on February 15, 2013, 12:13:43 PM
How about coating the cables with Rat Poison......73 K1WJ

That would work, till it rained or till the neighbours cat/dog was unexplainably poisoned  ;D


Title: RE: Hidden antenna options ?
Post by: WB6BYU on February 15, 2013, 01:00:05 PM
I'll wait until we get moved in and I see how much of a problem I have
to deal with.  If they get into the vegetable bed then it will be more of
an issue even if they leave the coax alone.  At this point it doesn't appear
that they are getting on our roof, and I'd like to keep it that way.

The first thing I'm going to try surrounding the coax with is the house
itself:  putting the feedpoint inside the attic and just bringing the wires
out through a vent screen, then tucking them under the shingles or under
the eaves where they are out of reach.

Playing recorded hawk cries through a small speaker mounted on the roof
may also encourage them to seek shelter elsewhere.

Next step would probably something that smells or tastes bad:  chilli
pepper oil mixed with roofing tar perhaps.  We might add some large cat
"scent" (some zoos collect it from their tigers and lions and sell it as
a deer repellent) to further discourage them.

If it becomes necessary I might resort to running a second wire charged
to 150VDC / 1uF or so in parallel with the antenna wire, arranged so they are
likely making contact with the former when chewing on the latter.  It certainly
was effective for the tom cat that used to visit us for meals without an
invitation.  Not enough to do damage, but sufficient to discourage repeat
visits.


Title: RE: Hidden antenna options ?
Post by: W6UV on February 15, 2013, 03:10:16 PM
But the neighbor feeds the local squirrels on top of the fence, so I'm considering ways to discourage them.

A pellet gun will discourage them permanently.


Title: RE: Hidden antenna options ?
Post by: VE3FMC on February 16, 2013, 06:29:16 AM
I must have coax friendly squirrels around here.  ;D I have had a run of coax across the roof of my house for the past 5 years. No problems with the little rodents chewing on it. I have 3 runs of coax, plus a rotor cable running along the wood fence in my back yard and it has not been chewed.

I have a pair of squirrels that live in a tree in my front yard. In the spring I am going to make them relocate! I think I can reach their living quarters, if so it is going to be destroyed. They can move some where else.

Although they are entertaining to watch as they run around the trees in my back yard. Caught them doing the nasty one morning on the one maple tree out back.  ;D It was funny because they are grey and a black squirrel tried to get in on the action and was chased up the tree.

Hey maybe I should leave these ones alone, they have not chomped the coax runs. If I boot them out and new ones move in they might have a taste for coax and wire.


Title: RE: Hidden antenna options ?
Post by: K0JEG on February 18, 2013, 05:45:13 PM
I've heard that painting coax fluorescent green will keep them away from cables, because they don't chew green wood. The problem with just about any chemical solution is that it will either wash off or require the varmint to break the jacket, depending on how it's done. If it washes off you'll need to keep on it, if they chew through the jacket you end up replacing anyway. And capsaicin flooded coax won't be easy to find anyway.

I'd say running it in schedule 40 conduit might help a little. As long as you keep the ends covered it might be a little harder for them to get started chewing, and they might not realize they can try.

And are you sure the neighbors are feeding the squirrels? They might be trying to feed birds.


Title: RE: Hidden antenna options ?
Post by: AB1XG on February 19, 2013, 04:01:24 AM
Back to the drawing board...  

A full 20meter loop was installed around the perimeter of my back yard fence, roughly 6 feet from the ground, a 4:1 ballon was used to bring the antenna in the house via RG8x coax. All was well until a chipmunk decided to have a
taste of the copper wire !!

A new chipmunk safe antenna design is required !

73
Demetre - VE3/SV1ENS

Not good! Try substituting barbed wire, lol!

David N1ZHE


Title: RE: Hidden antenna options ?
Post by: KH6DC on February 24, 2013, 08:45:26 PM
But the neighbor feeds the local squirrels on top of the fence, so I'm considering ways to discourage them.

A pellet gun will discourage them permanently.

Or a 44 magnum  ;D


Title: RE: Hidden antenna options ?
Post by: K0JEG on February 25, 2013, 09:24:47 PM
But the neighbor feeds the local squirrels on top of the fence, so I'm considering ways to discourage them.

A pellet gun will discourage them permanently.

Or a 44 magnum  ;D

At almost $0.70/round that's an expensive way to get rid of vermin. And you'd better be a fairly good shot, too.


Title: RE: Hidden antenna options ?
Post by: W1JKA on February 26, 2013, 07:53:45 AM
  Get rid of squirrels and chipmonks on the fence the easy way,just affix a copper penny on top of rail about every 3 ft.They don't like the smell of the chemical reaction between copper and wood resins,especially cedar or pine.Similar to the age old remedy of putting hair clippings from the barber shop around the perimeter of your garden to keep out deer or other pesty animals.


Title: RE: Hidden antenna options ?
Post by: WB3HUS on March 27, 2013, 06:38:38 PM
Hi all,
I have the same problem as all the other guys. I live in a trailer park and the owner is a problem. she thinks since my trailer is on her land she can stop me from doing my hobby, Im going to string a 1/2 wave 80 mtr dipole on my roof with parts under the shingles with the holders that you would use for xmas lights. my trailer is ~65 to 70 feet long it has a peaked roof (wooden) now my question is: " can I bend the dipole straight down the center of the roof, then at the end bend it at ~90 degrees and the same at the other side to take up the other 60 some odd feet of antenna". will that affect my pattern, it will be about 12 + feet above the ground.

thanks
wb3hus


Title: RE: Hidden antenna options ?
Post by: WB6BYU on March 28, 2013, 09:14:18 AM
You can take a lot of liberties with dipoles and they will still work better
than the same amount of wire coiled up on the shelf, even if the pattern
and/or performance doesn't match the ones in the antenna books.

The best method I've found would be to put the feedpoint in the center
of the roof and run the wires down to opposite corners.  At that point
bend it around the corner along the short end of the trailer and continue
on around the perimeter as needed.  You'll a few more feet of wire than
the standard formula, and there may be some advantage to putting a
loading coil somewhere near the first corner to reduce the total length.
(Make it the same on each end - you can then adjust the coil to tune
the antenna rather than the wire lengths if that is more convenient.)

The SWR may be on the high side at resonance, as the feedpoint impedance
may be in the 20 to 30 ohm range.  But with the wires tucked under the
shingles it shouldn't be very noticeable, especially if you use thin wire that
matches the roof color.


Title: RE: Hidden antenna options ?
Post by: WD4ELG on March 28, 2013, 10:38:56 AM
W1JKA, that is terrific guidance!  Thanks.

WB3HUS, that should work...especially since I see so many folks leaving their Christmas lights up all year long!

Mark Lunday, WD4ELG


Title: RE: Hidden antenna options ?
Post by: WB3HUS on March 28, 2013, 03:04:40 PM
thanks guys,
I will give it a try that is what I was thinking of doing. You say that to try to get the middle of the dipole in the center of the roof. and run it to the end of the roof and bend it at approx. 90 degrees on each end. Can this be done with a multiband dipole for 80 and 40 and maybe 20mtrs. also can this be done with one that I purchased  if I do so.you can answer this at my email address: rb622b@aol.com this way we wont take up space on this post.

Thanks
rich(wb3hus)


Title: RE: Hidden antenna options ?
Post by: WB6BYU on March 29, 2013, 09:32:58 AM
Yes.