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[Articles Home]  [Add Article]  

6M Square Copper Dipole

K0FF (K0FF) on September 14, 2000
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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 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), and 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.

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" 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" 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. Attatch the center conductor of a 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.

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.

*Parts are available in a kit from author which includes all "*" parts, drilled, punched, bent, and threaded, Contact George @ K0FF@ARRL.NET

Don't Eat the Batteries" clause:

Recently my wife and I bought a new TV set, and in the instructions for the hand held remote control the warning said "Don't Eat the Batteries".

SO:

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 K0FF

Member Comments:
This article has expired. No more comments may be added.
 
Great article  
by NC3Z on September 14, 2000 Mail this to a friend!
Halo's work amazingly well on 6M. If you are short on space this is what you need.

Great article!
 
the square dipole  
by K4JRB on September 15, 2000 Mail this to a friend!
This is an updated version of the old Squalo. At one point
you could own a squalo tree with versions from 2 to 40 meters. Herb Brier, the Novice editor for CQ in the early 70's, had a wire square dipole for 15 in his column. He added 360 ohm reactance in the middle of the sides to give the dipole directivity off the front so you could rotate it.
I used a wire version (actually rectangular) for 80 with a create 80 meter short rotatable dipole as a reflector fed HB9CV style as an effective antenna. The beam came down in a storm but while up I worked pile ups with ease although only up 70' or 1/4 wavelength.

The square dipole is an efficient antenna for limited space.

Dave K4JRB
 
Great Article  
by N8WP on September 16, 2000 Mail this to a friend!
That was a great article. I am a little fuzzy on the gamma match. I am not quite certain how to set it for max performance, or how to scale to to 2M. I am going to experiment with that same design on 2M.

73,

Willie
 
Great Article  
by N8WP on September 16, 2000 Mail this to a friend!
That was a great article. I am a little fuzzy on the gamma match. I am not quite certain how to set it for max performance, or how to scale to to 2M. I am going to experiment with that same design on 2M.

73,

Willie
 
 
by KF4ZGZ on September 17, 2000 Mail this to a friend!
Sounds good ! Being a antenna buff , I would like to see the formulas used to arrive at the lengths. Usually when I experiment with antennas I try them on several bands.
Have you tried it mounted vertically ? ( or anyone else )
 
RE: More Info from K0FF  
by K0FF on September 17, 2000 Mail this to a friend!
The basic design of this series of antennas is straightforward, but to make such a high "Q" antenna work in the real world, a lot of cut-and-try time was invested to teake them. The final design was arrived at after a great deal of experiments, and on the air tests, with over a dozen test models built. The 2M version was even worse. Once the "magic" was solved, all efforts were made to make them reproducable, but you must follow the directions exactly to arrive at the same results. If any one can start from here and improve them in some way, please let me know. Otherwise a tried and true antenna can be had inexpensivly if you follow the instructions to the letter. I personally made over 40 units of both the 6 and 2 meter versions so far and are in service all over the world, not to mention countless clones. Happy Building, and above all be safe when working with antennas. **NEXT: The 2M version.
Don't waste too uch time trying to scale this design directly to 2M, it's not do-able per-se, but a simplified version works great,and is even easier and less expensive to make. As far as performance, I have worked mobile-to-mobile 200 miles on 2M SSB with them! Also they make a dynamite uplink antenna for AO-27, hi and overhead passes.
On both 6 and 2, you can stack them for gain/higher power rating. Geo>K0FF
 
Squalo Redux  
by AC3P on September 19, 2000 Mail this to a friend!
Great article.

I am still using the original squalo I bought in 1968. It's the mainstay of my 6 meter operation at the moment.
It's to bad Cushcraft stopped making them.

How about some dimensions for the 10 and 2 meter versions?

73

AC3P
 
RE: Squalo Redux  
by W9DZ on September 22, 2000 Mail this to a friend!
For a while, after CushCraft stopped making them, they were being produced by the H.C. Van Valzah Co. I used to see Howard at most of the hamfests in the Chicago area and at Dayton. He went out of business a few years ago and I don't know if he is still around. I can't find him in the database at QRZ.COM.

I still have one of his 2M squalos in the blister pack.
 
Detailed Photos of construction located at:  
by K0FF on September 30, 2000 Mail this to a friend!
http://homepages.dstream.net/K0FF/HomebrewTips

Happy Building, Geo>KFF
 
RE: Detailed Photos of construction located at:  
by K0FF on March 26, 2002 Mail this to a friend!
Sorry, the web page is down after the ISP sold out. I will try to find a new home for the pix. Meanwhile I will be glad to eMail or US mail copies. Geo
 
6M Square Copper Dipole  
by K0FF on December 18, 2002 Mail this to a friend!
*************************************************

*************************************************

THIS ARTICLE HAS BEEN MOVED TO #4319 DUE TO BROKEN INTERNET LINKS TO THE PICTURES>
http://www.eham.net/articles/4319



FOR FURTHER INFORMATION ON THE HARDER TO FIND PARTS GO TO
http://www.qsl.net/k0ff


73 Geo>K0FF

 
6M Square Copper Dipole  
by KB0LEA on May 14, 2005 Mail this to a friend!
Recently built one of these and it is awsome. Thanks to K0FF.
 
6M Square Copper Dipole  
by K0UC on May 24, 2005 Mail this to a friend!
I started building one of the YEARS ago with info I got from Geo (Thanks!) and finally finished it today!

It tuned up like a champ and I heard a couple of beacons with it today. Will have to give it a workout in the June VHF contest.

Lowest I could get mine to resonate initially was about 50.8, so I made the butterfly a little longer (1/2 inch each side) and she went right down to 50.2!
I may have miscut a copper pipe a bit. My gamma match required no adjustment and I have 1.2:1 SWR.


It's a mechanically strong design and looks nice (to hams I suppose!).

73 and thanks again Geo.

Brady
 
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