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KC8OPV Skywire Loop Antenna
Note: This antenna has yet to be implemented. Other priorities have preempted the construction. Read through the discussion anyway, since it contains some very valuable information.

Image of Proposed KC8OPV Skywire Loop Antenna

I'm looking for feedback on this antenna design and your expertise is appreciated! Please e-mail me at or leave feedback at the eHam.net forum.


The following are comments already received via the eHam.net Forum.



Skywire Loop Antenna Reply
by KC8OPV on May 23, 2002 Mail this to a friend!
I'd appreciate any feedback from those who know about or have experienced using full wavelength skywire loop antennas.

I am looking to put one up in the near future and I'm curious on the performance. Also, because of yard/tree placement, I can't have it in a perfect square configuration (will look more like a arrowhead). What kind of performance can I expect with this configuration?
How will the radiation pattern look?

I'm thinking the antenna will be about 30-40 feet off the ground and fed with ladder line to a 4:1 balun, then into an antenna tuner. Also, it will be about 250' feet long (about 20' short of a full 80M loop).

Please see http://www.qsl.net/kc8opv for details (click on the Skywire Loop Antenna link).

Thanks!
 
RE: Skywire Loop Antenna Reply
by WB2WIK on May 24, 2002 Mail this to a friend!
I looked at your proposed installation -- nice work on the drawing!

The obvious question that comes to mind is, since you intend to occupy "most" of your yard with this anyway, why not go the rest of the way and just completely encircle the perimeter of your yard with the loop? That would be about 375 feet or so, and being more rectangular in shape, is much easier to model.

If, for some reason, this is impossible to accomplish, the only recommendation I'd make which differs from your intent is to eliminate the "coax" from the system altogether, and bring the ladder line directly to the tuner BALANCED terminals. Even if those terminals use a balun inside the tuner, that's fine -- the balun should be inside the tuner, not outside it, for maximum efficiency.

On any frequency where the loop poses a very high impedance, even using a 4:1 balun and coax will result in severe mismatch on the coaxial run, and the resultant substantial losses. On any frequency where the loop poses a very low impedance, using an external balun to transform that to something even lower is likely to make the system impossible to tune.

Bringing the balanced line right to the tuner is the best way to minimize these problems.

WB2WIK/6
 
RE: Skywire Loop Antenna Reply
by KC8OPV on May 24, 2002 Mail this to a friend!
Thanks for the feedback. Unfortunately my tree restrictions and power lines limit me to the configuration I have designed. Will I suffer any problems from it not being in a square or more round configuration?

Thanks
 
RE: Skywire Loop Antenna Reply
by KD4LHA on May 24, 2002 Mail this to a friend!
I had a Loop skywire antenna a few years ago, until a storm blew down everything I had up. It was the best listning antenna I ever had. I suspect shape is important, mine was a iregular pentagon and worked well for both xmit and recieve. I also used 450 ladder line to a Balanced feed from a tuner, Good Luck, Bob
 
RE: Skywire Loop Antenna Reply
by KC8OPV on May 27, 2002 Mail this to a friend!
Thanks for the comments Bob. I'm a bit concerned about the shape, but otherwise I think it will be a good performer...

James
 
RE: Skywire Loop Antenna Reply
by K3AN on June 4, 2002 Mail this to a friend!
1. Don't worry about shape. I installed a loop in a triangluar configuration, and it was the best wire antenna I ever used (G5RV and OCF dipole are tied for the worst performance, in my experience).

2. If you cut the loop's overall length to resonate near the bottom end of 80 Meters, there will be no extremely high or extremely low impedances on any of the harmonically-related (traditional) HF bands. This in turn will prevent excessive losses in your balun. Baluns always have more loss when they're not working into their design impedance.

 
RE: Skywire Loop Antenna Reply
by KC8OPV on June 5, 2002 Mail this to a friend!
I'll heed your advice on antenna length and the balun.

I am currently working on ways I can put up a post in the backyard to be able to lengthen the antenna a bit.
 
RE: Skywire Loop Antenna Reply
by VE1CHS on June 10, 2002 Mail this to a friend!
Hi,

I'm Peter, VE1CHS, currently retired mostly in Colorado.

Putting up the loop:

I used the available pine trees on my 2 acre neighborhood home site, on a 30 degree mountain slope at 9000 feet above sea level. I did not worry about the total perimeter. My entire property is on the side of a mountain, and I did not worry about the fact that one end of the loop is higher than the other. I simply used 5 trees, in roughly a square or pentagon, at the edges of my property. I used a plastic bow bought at K mart, and arrows in the hunting section. I used a casting fishing pole with a good reel and 6 lb test line. I tied the arrow to the fish line, and braced the rod in my feet, and opened the reel for casting mode. I shot the arrow over a pine tree After the shot, if you can't see the arrow, jiggle the fishing pole and let out line, and soon you will see the arrow near or at the ground level. It will thread itself through any branches. Then haul up nylon rope by tying the rope at the end where the arrow was, after it has gone over the tree near the topmost branch. You just reel in the nylon rope as it goes over the pine tree in the exact spots the fishing line was in. It often takes several tries with the bow. After each attempt, simply cut the arrow from the line, and reel in the line, tie on the arrow, and then shoot again. (Do not try to reel in the arrow if you don't like your shot; it will get caught in the branches and the fish line will break, leaving the arrow high in the tree). Best done with no wind, for wind will make it hard to get a shot and good line placement over the top most part of the pine tree.

You would be amazed how high up you can shoot an arrow with light 6 lb test line attached. You can really get your loop up over the higest tree tops.

Once I had a shot I was satisfied with, and a nylon rope in place, I tied an insulator I bought from radio shack on one end, and then fed #14 wire through the insulator, and hauled it up by pulling on the other end. You then string the wire to the next insulator from the next tree.

If there are other trees in between, just thread the wire by shooting an arrow over the obstacle trees and branches, then thread a nylon rope, then thread the wire.

I used two hammered in nails on the tree about 8 inches appart, to wrap the rope around as I hauled the the insulator up high in the tree near the top. This allows precise adjustment of rope from each pine, and future maintenance. Leave about 4 to 5 feet of rope length out from the topmost tree branch, so the antenna is 4 to 5 feet from the top of the tree.

If you misjudged the length of wire needed, too short or too long, simply lower your support ropes, and lengthen or shorten the wire in the loop, until you have it right.

My neighbors and I are all ardent environmental whackos, you know, "Sierra go home!" types, so I dyed my nylon rope black, and painted my insulators black. No cop cars so far, and at Xmas parties, my neighbors appreciate the fact that my ham radio QRP station is set for any neighborhood emergency (I Labs QRP plus, a motor cycle battery; soon a K2).

Loop maintenance:

Now, storms and wind are going to rub the nylon rope up against branches over time, and create frayed areas which will eventually break. Be proactive: My rope supports last about 18 months. Best to just have a maintenance day, and lower all your rope, and replace it with new rope every 15 months.

I got lazy, winter high winds took down several supports (frayed areas broke), and I had to put in a lot of time re-stringing my loop. Had I done more regular maintenance, this would not have happened.

The wire won't break, because of the natural spring action of the trees and the branches through which the rope is strung. Leave a little slack in the loop, for those wind storms.

Feeding the loop:

I feed the skywire loop with brown twin lead (300 ohm?) twin lead I bought at radio shack. It's not the light 300 ohm twin lead, its the heavy stuff they sell. It just happened to be fed near one end, but that doesn't matter. It wouldn't matter whether it is 450 ohm fancy black spaced feed (I had some of it once), or 600 ohm twin lead feed, or light 300 ohm twin feed.

I coated the twin lead where it is attached to the loop ends with JB Weld to keep the feed wire from stress bending and breaking in the wind at the attachment points. A radio shack insulator brings both ends of the loop together (yet insulates them) where each loop end is fed with one end of each 600 ohm twin lead.


I use an old MJF Versa Tuner II model 949D, not a high quality tuner. (I had to replace one washer with a printed circuit epoxy glass washer I hand cut after taking off the copper foil, because the previous owner had blasted the tuner with hundreds of watts and these had arced through). This tuner has a built in balun, and allows you to feed out a balanced feed. Very handy. Be sure your tuner has balanced feed output capability, so you don't have to fool with a special balun.

I can tune every band except 160M. If the perimeter, as one poster said, were longer, I could tune that band as well. So, make the perimeter as long as your property allows.

You don't think much of QRP with a skywire loop, my friend?

Here at 9000 feet up, with a clean 180 degree SW and W vista and shot across a valley below, with 13,000 foot peaks at the continental divide 7 miles to the west, you'd be amazed.

I blast right through (or over) the western 13,000 foot peaks to CA and NZ and AUS on 30 M at 2 or 3 AM local time.

I work the NW into Washington and western USSR. I've hit the Mariatius Islands off the coast of Madagascar, litterally on the other side of the world. Worked South Africa. Worked into the Carribean and Argentina, to the South East. I've made it often into the USSR over the northern path, and through a neighbor's home, higher up than me, that is supposedly "blocking the way"!

One day, a ham near Phoenix (700 Miles mostly south) and I on 40M, daytime skip, lowered our power to 50 Milliwatts CW. I was still S3 at his end!

73s, [email protected]

 
RE: Skywire Loop Antenna Reply
by N3BIF on June 10, 2002 Mail this to a friend!
Good comments Peter, you dont say how big your loop is but if it is at least 270 feet you should be able to tune 160 with your tuner, take both loop leads on your feed line and attach them to your unbalanced terminal and this will cause your loop to work against the ground and you should be able to get out about 500-1000 miles, goodluck !
 
RE: Skywire Loop Antenna Reply
by KC8OPV on June 26, 2002 Mail this to a friend!
Just a quick update to my skyloop plans.
I had the opportunity to construct, raise, and extensively use an 80m skyloop this past weekend for field day. It was approx. 290 ft., raised about 40' in the trees.

In short...I was impressed!
We operated on most HF bands and it helped us break through most pileups in 1 or 2 calls.

I'll be excited to finally construct one of these for my home QTH.

James, KC8OPV
 
RE: Skywire Loop Antenna Reply
by STUDYING2BE on July 10, 2002 Mail this to a friend!
I have a question on the Skywire Loop. I can string up maybe 1100ft + of wire. As long as I use strong enough wire to support itself,Is there any advantage to making one longer than a full wave 160? What about splicing 2 pieces together for a single run? Other than making sure the splice holds and makes a good connection, would there be any problems with splicing? Thanks for your help in advance.:)
 
RE: Skywire Loop Antenna Reply
by KC8OPV on July 10, 2002 Mail this to a friend!
I'd say, the longer the better! You might want to make it a multiple of a wavelength...such as 2 wavelengths at 160m so that it resonates on the fundamental frequencies.

Another (perhaps more important) point to remember is to get it up HIGH off the ground. The higher off the ground the better your signal will be heard and the less ground interaction/loss you'll have.

As far as splicing the wire, go for it! Just make a good solid connection and solder it for longevity. I had to do this at field day this year because I had my loop constructed but there was a tree in the way. So we just snipped the wire, brought it around the tree and re-soldered the connection. Not a problem.

Let me know how it goes.

James, KC8OPV
 
RE: Skywire Loop Antenna Reply
by STUDYING2BE on July 13, 2002 Mail this to a friend!
Thanks James!! I'll only be able to use it for RX until I get my General,But trying to get everything set up for when I do.:) 73'S ,Mike
 

 


Created by James Wiersma, KC8OPV

Page last modified: March 24, 2003