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6 & 2 Meter Square Copper Dipoles

K0FF (K0FF) on December 18, 2002
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KFFs Homebrew Tips:




The 2 meter Square Copper Dipole by KFF

Originally published and copyright by KFF 5 Dec 2000 on eHam

Construction Detail

Here is the parts list and dimension sheet for a 2m square dipole, made from copper plumbing fittings and 1/2 inch copper water pipe.

It is more or less omni-directional, and horizontally polarized. You can even make it from the short pieces of pipe left over from the 6M project (see eHam how-to article "6 Meter Square Copper Dipole by KFF").
The antenna presents a low-through-high angle of takeoff, and is intended for use in the 144.200 area, although its wide enough to use as an AO-27 uplink, and can handle 100W. Its particularly useful on AO-27 when the pass is very high or overhead, and in the "cone of silence" of a fixed vertical. I use this for mobile satellite uplink, and wave a short hand-held 430 antenna out the window for receive. Excellent results from SSB mobile too, where Ive been able to talk to other mobiles similarly equipped 200 miles away. The mounting arrangement allows it to be affixed to a standard mobile mast that presents a 3/8 x 24 male thread (ALA Hustler base mast). You run coaxial cable right to the antenna and connect it to the built in SO-239.
The only adjustment on it is the Gamma match, as the design dimensions set resonance. You may want to adjust the final SWR by sliding the end caps in or out before soldering them.

Brass Parts

It's just a dipole folded around on itself.
The shape is an open 11 inches with mounting via a copper TEE with the open end down. In that open end solder a 1/2" brass rod, which has been drilled and tapped for 3/8-24.
For stacking a pair, you could make the TEE and threaded insert come horizontally instead, and mount one antenna above the other. (Future articles will give detailed info on stacking antennas in general). Stacked antennas provide improved gain and power handling capabilities.
Side mounting on a tower can be achieved by using conduit clip large enough to go around the mast (or tower leg), and run a 3/8 x 24 s.s. bolt into the threaded fitting.

Copper Parts

Solder the antenna parts together per the drawing using the 90 degree elbows at the corners. Cap the far (open) ends and mind the gap. All measurements are critical. The brass plate* to hold the SO-239 is bent to form an "L" 1-3/4" tall with a 1/2" lip. A 5/8 hole is provided 1-1/4 inch from the bend, and the SO-239 is attached using stainless steel or brass hardware*. Two small holes are drilled in the lip and the plate is mounted to the copper TEE with #6 s.s. Self-taping screws*. Solder a ring lug* to the center conductor of an 11" piece of RG8 insides* and screw it into the threaded coupling* on the SO-239 *(center wire and plastic dielectric only- remove and discard shield and outer covering). Slip the RG8 insides into the 3/8" copper tube* 4-1/2", and tap the copper tube to the radiating element 3-1/2" from the SO-239 center, with a copper strap bracket *.
The tap on the Gamma sets the impedance presented to the feedline.
Resonance (center frequency) is designed into the measurements.

Parts Placement

Gamma Tap

Parts for Gamma, both 6 and 2 Meter Versions




Materials List:

1/2 inch copper water pipe:
2 ea. 3 1/4 inch (capped end)
2 ea. 4 1/4 inch (TEE end)
2 ea. 9 1/2 inch (Sides)

4 ea. 1/2 inch copper 90 degree elbows*
1ea. 1/2 inch copper TEE*
1 ea. 1/2 inch copper caps

5 inches of 3/8 inch copper refrigeration tubing ( Gamma Tube)*
6 inches of RG-8 insides with solder lug*
Brass Plate for Coax connector*
1 ea. SO-239 with Brass threaded insert*
1 ea. Brass rod, threaded for 3/8x24 for mast attachment*
1 ea. 1/2 inch wide copper strip ( Gamma tube bracket)
Misc. stainless steel screws and hardware*

Nearly Complete

Have fun on 2 meters -- Geo, KFF

The 6 Meter Copper Loop




Here is the parts list and dim. sheet for a 6m Square Copper Dipole, made from copper water pipe.

Characteristics:
It is more or less omni-directional, and horizontally polarized.

Copper is the best possible electrical conductor at normal temperatures, next only to silver.
Copper conducts better than gold! Antenna efficiency is the RADIATION RESISTANCE of the antenna, divided by the ELECTRICAL RESISTANCE. An antenna made from copper is 1.6 times more efficient than the same antenna made of aluminum.

It presents a high angle of takeoff when mounted low, and singly (great for Es), can handle 100W. Stack two or more for extra gain if needed.

It's just a dipole folded around on itself, and supported at the far (open) end with a plastic insulator.
"Bent Dipole" might be a good term, as a "Folded Dipole" is quite another thing.

The Gamma Match:

A low VSWR may be obtained by adjusting the Gamma Match shorting bracket position, and also the length of the tubing and shorting bracket. The Gamma bracket "finds" the 50 Ohm point along the element, and connects that to the Coax connector via the Gamma tube. The additional length of tube adds inductance into the circuit, and this is canceled out by the series capacitance formed between the insulated Gamma wire and the inside of the Gamma tube.

Description:

The shape is a closed 28" square, with a mounting /support bar through the middle. This mounting bar is attached to a copper TEE at the drive end, and to a CPVC TEE at the other end. The CPVC TEE acts as support and end-insulator for the radiating element and provides a mounting point for the Butterfly.

Insulator:

A large (3/4") part is used, and adapted down to fit the water pipe, to increase its insulating qualities, as there is very high voltage at this point. A strip of brass or copper 1/2 by 3" is screwed to the outside middle portion of the CPVC Tee, through a small center hole, and is rotated one way or the other as a resonance tuner (Butterfly). When the Butterfly is at right angles to the element, the frequency is the highest, when Parallel, it's the lowest.
A Gamma match sets the impedance to 50 Ohms, and the Butterfly adjusts the center frequency. Center frequency is 50.00 to 50.800 with the exact dimensions shown Typically the 2:1 SWR bandwidth exceeds 500 kHz.

Mounting:

A U-bolt and saddle through the central tube provides a center mounting point. Another approach is to install a copper TEE in the center tube, with the open end down. In that open end solder a 1/2" brass rod which has been drilled and tapped for 3/8-24.

Side mounting on a tower can be achieved by using conduit clips to fix it to a horizontal mast.
In some climates where water is a problem, drill small weep holes in the bottom corners. A spray coat of Krylon Clear Enamel will keep the copper shiny. If used mobile, you may use a colored paint, the same shade as your vehicle.

Construction:

Material:
1/2 inch Copper waterpipe:
3 ea. 27 inch piece
4 ea. 12.5 inch piece

1 ea. 13.5 inch piece 3/8 i.d. Copper refrigeration tubing (Gamma tube) *
1 ea. Brass plate 1/2" x 3" (Butterfly) *
1 ea. Brass plate: 1"x 2-1/4 in (to mount SO-239, Gamma rod) *
1 ea. Copper strip 3/8 x 4" to make Gamma tube bracket *

4 ea. Copper 90 Degree elbow
1 ea. 3/4 CPVC TEE
3 ea. 3/4 to 1/2 CPVC reducer
1 ea. Copper TEE
1 ea. 11 inch piece of RG8 insides (center conductor and insulation, Discard shield and outer plastic) *
1 ea. SO-239 coax connector (with tapped mounting holes and center pin) *
1 Lot Stainless Steel and Brass screws and Hardware *

Glue two of the 12.5" pipe sections into the CPVC reducers first, then glue the reducers into the opposite sides of the CPVC TEE.
Lay the assembly on a flat surface with the center opening of the TEE facing the middle of the antenna. This is where the first 27" piece (mounting bar) goes in, via a reducer. On the outside edge of the CPVC TEE is where the butterfly attaches. For mobile or portable use, use 3 s.s. #6 screws through each of the CPVC TEE joints for added strength.
The rest of the antenna solders together to form a square, using the 90 degree elbows at the corners. Drill small weep holes in the bottom corners of all four 90s to let accumulated water drain out.

The brass plate is bent to form an "L" 1-3/4" tall with a 1/2" lip. A 5/8 hole is provided 1-1/4 inch from the bend, and an SO-239 is attached . Two small holes are drilled in the lip and the plate is mounted to the copper TEE with #6 s.s. self taping screws. Attach the center conductor of an 11" piece of RG8 insides to the center pin (center wire and plastic dielectric only- remove and discard shield and outer covering). This is accomplished by soldering or using a screw if the SO-239 has a threaded center pin *
Slip the other end of the RG8 insides into the 3/8"copper tube 10.5", and tap the copper tube to the radiating element 13-1/2" from the SO-239 center, with the Gamma tube bracket.

The tap on the Gamma sets the impedance presented to the feedline. Resonance (center frequency) is adjusted by turning the butterfly.

The Butterfly:

Mount 15 feet or more high, for home use, and wherever you can for mobile. An antenna like this can be mounted 3" to 6" above the roof of a vehicle using CPVC, PVC or acrylic spacers with suction cups.

Have fun on 6 meters Geo, K0FF

WARNING * This is antenna is an electrical conductor. Contact with power lines can result in death or serious injury. Do not install this antenna, supporting mast or tower structure near any power lines, or where they could come into contact with power lines should the antenna or structure fall.

Geo, KFF

The First 6M DXCC from Missouri The Only Zero with 5BDXCC and endorsements for 160/17/12/6 Meters.

Member Comments:
This article has expired. No more comments may be added.
 
6 & 2 Meter Square Copper Dipoles  
by N6AJR on December 18, 2002 Mail this to a friend!
wow, nice article and well presented.. good photo's tooo thanks tom N6AJR
 
6 & 2 Meter Square Copper Dipoles  
by N4DFP on December 18, 2002 Mail this to a friend!
This is a GREAT article! I am really clad to see constructio articles. Its on the things I like best about Amateur Radio. Love the gamma match idea. It reminds me of my first 2m Yagi. As a newly minted Technician in 1980,I had a two meter rig (as I recall, an HW-202 with GLB synth) but no antenna to terminate it with. The Radio Handbook (Bill Orr, W6SAI) showed an example of a gamma matched 6m Yagi, which I thought I could scale down to 2m. I went for a walk on the back lot and found an old Lo VHF TV antenna in pretty good shape, so I got some 3/8" copper and made a driven element for it, and extended the directors and reflector using 1/4" copper. As I looked over my pitifully small collection of junk, I noticed that the 1/4" an 3/8" made a loose slip fit. It occurred to me that 1/4"ID neoprene tubing would just about take up the slack and make a dandy di-electric. With the help of a little dishwashing soap, I assembled the pieces and cut up and flattened a piece of old brass plumbing pipe to mount the SO-238 to the driver. I mated it all together and got an immediate 1.1:1 match and was even tolerably well matched on the Army MARS split. The antenna worked beautifully; so well that I had no problem reaching the Mt Mitchell, NC repeater from Camden, SC... about 150 miles.
 
RE: 6 & 2 Meter Square Copper Dipoles  
by CURMUDGEON on December 18, 2002 Mail this to a friend!
I also applaud. Contary to popular belief, Curmudgeon doesn't always feel negative.
 
RE: 6 & 2 Meter Square Copper Dipoles  
by W7KKK on December 18, 2002 Mail this to a friend!
Very nice article. I do have one question. Did you use the acid core solder that you would normally use with copper pipe for contrauction or would it perhaps be better to use either a silver or electrical type solder for the job?
 
6 & 2 Meter Square Copper Dipoles  
by WR8Y on December 18, 2002 Mail this to a friend!
I'll bet this one will stand up to the wind and ice...
 
RE: 6 & 2 Meter Square Copper Dipoles  
by WB2WIK on December 18, 2002 Mail this to a friend!
This was just great!

Question to the author: Have you tried using a balanced feed instead of the Gamma? The Gamma represents the classic "unbalanced feed of a balanced antenna," so is great for easily matching coaxial transmission line, but in experimenting with Yagi feeds years ago, I always achieved better performance going to a T-match, or some balanced feed system, using a balun to step the Z back down to 50 Ohms for coaxial attachment.

In one case documented at the Central States VHF Society in the late 1970's, simply changing the "Redi-Match" (Gamma) on a Cushcraft 2m Yagi to a T-match and balun resulted in > 3dB measured forward gain improvement.

Anybody tried this with a loop?

Again, great article.

WB2WIK/6
 
6 & 2 Meter Square Copper Dipoles  
by K0FF on December 18, 2002 Mail this to a friend!
Hello All, this is a reprint of the eHam article I first did back in Dec 2000. Due to broken internet links, we decided to combine the 6 and 2 meter antennas into one article. The 6 meter antenna is a reduex of the old Cushcraft Squalo, but the 2 meter antenn is an original design.
Please see www.qsl.net/k0ff for info on obtaining the harder to find brass parts.
73 and Happy Homebrewing

Geo>K0FF
K0FF@ARRL.NET
 
RE: 6 & 2 Meter Square Copper Dipoles  
by K5DVW on December 18, 2002 Mail this to a friend!
Awesome article, thanks!

I've built a few of these, as well as halo types for 2m. Good to see it documented so well.

K5DVW
 
RE: 6 & 2 Meter Square Copper Dipoles  
by W0FM on December 18, 2002 Mail this to a friend!
Hey George! Great project. Next time you're in St.Louis, call me.....I could use your help installing a shower stall in the basement!

Happy Holidays!

Terry, WFM
 
RE: 6 & 2 Meter Square Copper Dipoles  
by CURMUDGEON on December 18, 2002 Mail this to a friend!
Rosin core solder will do nicely!
 
6 & 2 Meter Square Copper Dipoles  
by N9RLA on December 18, 2002 Mail this to a friend!
Hi Geo & All,

I just wanted add my experience with this project. I built one of the 6m copper squares a year or so ago. After several thousand miles of Roving it's still working great! It is a very solidly built, durable antenna, which is a requirement for Rover use. It's performance compares very well with a full size dipole [that I've also used for Roving..] and is far better than a 2 meter 5/8wave mag mount [that will work on 6m in a pinch, but isn't much of a performer].

The great thing about these antennas is you can get amost all of the parts from your local hardware store and radio shack. Although I bought a kit from Geo to build mine. It saved a lot of time having everything in one bag, and the price was about the same:-)

Rosin core solder will work just fine, but it helps to have a lot of heat. I used a propane torch to heat the pipe. You will also need a quite a bit of solder, so a nice heavy gauge of solder helps. I had some 0.093" solder that worked well. The thicker the better here, I would say.

I can't wait for your next article, as I'm planning to build a second one and try stacking them:-)

73
Dan

Dan Evans N9RLA
Scottsburg, IN 47170
{EM78}
IN-Ham list administrator
QRP-l #1269
1/2 of the N9RLA /R no budget Rover Team
Check out the Rover Resource Page at:
http://www.qsl.net/n9rla
 
RE: 6 & 2 Meter Square Copper Dipoles  
by K9PO on December 18, 2002 Mail this to a friend!
Is there a pdf or word version available of this article? i would like to print out a few and hand them out at a club meeting and see if can get some interest to build a few of these.

73
Scott
 
RE: 6 & 2 Meter Square Copper Dipoles  
by N4ZOU on December 18, 2002 Mail this to a friend!
I can convert the entire Article into PDF format and post it on my web page for download if it's ok with KFF at no charge to anyone.
My page is located at www.geocities.com/n4zou
Please E-mail me stating it's ok.
 
6 & 2 Meter Square Copper Dipoles  
by DU1LWQ on December 19, 2002 Mail this to a friend!
Very nice project. Can I convert this article to pdf and post in our website (http://www.dx1mk.com)? I'm sure a lot of people would be interested to build this kind of antenna.

73 de Rei/DU1LWQ
http://www.dx1mk.com
Makiling Amateur Radio Society
 
RE: 6 & 2 Meter Square Copper Dipoles  
by K0FF on December 19, 2002 Mail this to a friend!
article located at:

www.qsl.net/k0ff

I think you can print it from there. The actual word document is huge. Let me know if it works for you.If not I can send paper version and you can xerox it, or even Word on a floppy.
Geo>K0FF
 
RE: 6 & 2 Meter Square Copper Dipoles  
by K0FF on December 19, 2002 Mail this to a friend!
This version of the combined article is copyright 2002 by GEOelectronics. The originals were copyright 2000 by GEOelectronics.
Distribute any of these articles freely and at no charge as much as you want, absolutely, in any way or media, as long as it's complete and unchanged and no charge beyond reasonable duplication expenses. No other restrictions. Further I would *appreciate* credit being given for the basic units if modifications are made. Have fun, I encourage all to make improvements and modifications. 73'
Happy Homebrewing

Geo>K0FF
 
RE: 6 & 2 Meter Square Copper Dipoles  
by N4ZOU on December 21, 2002 Mail this to a friend!
I started to download the article here to start converting it to PDF but none of the pictures will load this morning (Dec-21-2002). I also tryed to get the web page but it also will not download. I am sure the site where the pictures and your page is located is down at this time. I will try later and see if it's back up. If you could send a floppy to me and my address is good in the call server that would be best. I will return it to you with the article in PDF format. You could also try and attach the article to an e-mail. I can accept large attachments but I will not post that e-mail address here, you will need to send a request to my n4zou@hotmail.com address. Word format will be fine if it will fit on a floppy it can also be sent as an attachment. Also note that you must send a message first without an attachment with ~eXpeCt A fILe~ in the body of the message, otherwise my e-mail program will purge the attachment on the second e-mail. Be sure to copy and paste the pass text or carefully type it in.
 
RE: 6 & 2 Meter Square Copper Dipoles  
by N4ZOU on December 21, 2002 Mail this to a friend!
Everything is back up! I have the completed PDF file ready to upload on my Web page. Now all I need to do is edit the main page with the link to the file. I should have this done in about and hour...

www.geocities.com/n4zou
 
RE: 6 & 2 Meter Square Copper Dipoles  
by N4ZOU on December 21, 2002 Mail this to a friend!
Yahoo is not allowing my to upload K0FF's antenna project file. It acted strange when I uploaded the main updated page and now I can't even access it with the file manager. Give me a few days to try and get it up on the site. I can't even remove the dead link from the main page!
 
RE: 6 & 2 Meter Square Copper Dipoles  
by N4ZOU on December 21, 2002 Mail this to a friend!
Yahoo is not allowing my to upload K0FF's antenna project file. It acted strange when I uploaded the main updated page and now I can't even access it with the file manager. Give me a few days to try and get it up on the site. I can't even remove the dead link from the main page!
 
RE: 6 & 2 Meter Square Copper Dipoles  
by N4ZOU on December 21, 2002 Mail this to a friend!
OK! I got it working. The article link is...

www.geocities.com/n4zou/files/6n2loop.pdf

 
6 & 2 Meter Square Copper Dipoles  
by N6JSX on December 22, 2002 Mail this to a friend!
Nice to see another very GOOD technical "How-to" build-it article. But eHAM how about allowing us to download this article (like you did the simple 2m J antenna article) this allows us to keep and/or print the article without the side banner stuff that messes up the printing.
Guess, I need to get hot on some more J and combo inverted V articles. Been just to busy this year.
Kuby, N6JSX /8
 
6 & 2 Meter Square Copper Dipoles  
by KE4NYV on December 22, 2002 Mail this to a friend!
For those who wanted a .pdf version of this, I created one and posted it at www.ke4nyv.com/squaredi.pdf

73's
Jason KE4NYV
www.ke4nyv.com
 
6 & 2 Meter Square Copper Dipoles  
by K0FF on December 23, 2002 Mail this to a friend!
There have been some questions about the final dimensions. I think there might be a confusion as to where the measurements are taken from. When dealing with mechanical assemblies, I assume center-to-center measurements. That is from the center of one tube to the center of the tube on the opposite side. Assuming equal tubing diameters, inside-to-outside readings yield the same result.
Irregardless, there are some other variances due to the particular elbows and tees, and how deep they seat the tubing pieces. Best approach is to measure the resonance point with an analyzer or swr meter before final soldering. This goes for both versions.

In the spring, I'll give dimensions for a 222 and 432 version, and by the way, the basic layout Square Copper Loop for 6 meters can be scaled up for use on 10 meters with great results. A first prototype came in at 46-1/4" x 53" with the gamma tap at 21". As time allows, I'll refine the measurements into a square, and give details.

Yes the picture links went down not a day after this article was reposted. Something must have crashed at qsl.net, where the article pictures reside.
Many thanks to those who have generously duplicated the article on other sites.

Geo>K0FF

http://www.qsl.net/k0ff


 
RE: 6 & 2 Meter Square Copper Dipoles  
by KE5BQN on September 29, 2004 Mail this to a friend!
there is talk of a kit for this 2m antenna, where do you get a kit from and what kind of price am i looking at?
73's
 
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