| Tuesday, October 09, 2007 |
| Full Size Delta Loop for 20M |
I came across a simple delta loop design courtesy of dxzone found on the net some time ago and have been planning to give it a go for a while.
This weekend I had a couple of hours spare, so I decided to give it a go using some 2mm multi strand wire cable, a dipole centre and a mixture of 75 ohm and 50 ohm coaxial cable.
The delta loop is supposed to be resonant on 20 meters but I found it to be a little high so at present I am tuning the Loop with my mfj-969 which copes extremely well. The resonant frequency is 13.2 MHz at the moment so the next chance I get, I shall shorten the overall length making sure that each of the three sides are still equal in length, and hopefully adjusting the antenna for maximum performance ATU free for 14.2 MHz.
I believe the miscalculation in the resonant length is probably down to the fact that my wire is covered in the plastic sleeving from the manufacturer which always effects the swr as I have noticed in past experiments with dipoles you always get slight differences with sleeved and bare wire lengths, for accurate resonant results you will benefit by using bare hard drawn copper cable without sleeving. If you are into playing around and adjustments like myself plastic sleeved cable is a superb and cheap way to get the job done.
The basic layout of the 20 Meter Delta loop, each side is 7.71 meters in length with the feed point 3/4 of the way down one side (5.78 m from the top) fed by a quarter wavelength of 75 Ohm cable (3.5m long) which is connected to a 50 Ohm cable coax into the ATU
Despite having to use the ATU at the moment I am getting some great results and signal reports with QSOs being made into Alaska, Canada, Azores, Belarus, Italy and Slovenia.
The information given at dxzone recommends that the Delta Loop should be suspended vertically with the assistance of some tall trees. Unfortunately The trees near to my QTH are not so tall, so I decided to try the Loop in the horizontal position instead and like I said so far so good.
If you are thinking about trying one of these antennas you will not be disappointed and there is more info available at
Homebrew 20 Meter Delta Loop
Good luck and let me know how you get on all comments are appreciated.
I have been comparing the Delta loop to the G5RV and Hustler 6BTV, it's early days but seems to be working well on the 20 meter band. The Delta Loop and 6BTV both terminate at a two position switch which allows me to switch between the two antennas very easily.
73 to all and thanks for visiting Ham Radio, good Dx de 2E0HTS Simon in Yorkshire, North England. |
posted by MØYKS Simon @ October 09, 2007  |
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| 10 Comments: |
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I have been using the loop vertically polarized for the last two years with amazing results and very little noise.
de Simon 2E0HTS
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Simon, if I modify your antenna by placing the long axis on top and the feed point at the lower apex should I not have similar performance? Will this not result in the current being at the top of the antenna on this upper leg of the loop? The top leg will 35 feet agl. I will feed it with 450 ladder line and to a balanced tuner.
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Hi Chris sorry for the delay. I have found that the best configuration is when you have the most area inside the loop. it does not matter to much where the feed point is or what shape the loop is as the best results are gained with the largest inside area that you can get.
Let us know how yours works out G L thanks and 73
Simon
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13 cm off each leg will make it resonant on 14.2mhz
Seymour ZS1CPT
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Chris my calculations show that
7.71 meters per side is too long
If you use 1005/14.200 you come
Up 2 feet shorter or 23.59’ per side
It will put you in the middle of 20m
Without a tuner.
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As someone new to DIY construction of this Vertical Loop Antenna, I am thinking that wrapping the wire around itself two turns at each corner egg shape insulator might add some simplicity in construction as well as eliminating the wire from sliding, creating unequal length sides. Any harm in doing this?
Ian. W4IDA
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Hi Ian, I would probably not wrap the wire around the insulator, instead I would suggest running the wire through the insulator but fixing it in place with a cable tie. It will help to keep the radiation pattern more effective. Some may disagree but I would use cable ties. Have fun and hope it works out de M0YKS Simon. 73
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I built one but need to deploy it
I have a fiberglass military mast fot the center point and fence stakes in the ground for the other 2 points .I have a plastic pulley on all 3 points with the lower 2 attached to the stakes with long bungie rope. With this setup I can easily adjust the feed point just by moving it on the pulley system
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Simon - thanks for the write up. Out of interest how high is your horizontal loop? Also if you don't use the 75 ohm cable - you get a multiband loop with your tuner.
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