I found this on the internet. ZZ Wave Net. This is a dual band loop antenna covering 80 and 40 meters.
I have been using a horizontal loop at 30 feet for over a year now and also have experience with a 40 meter delta loop. The 40 meter delta loop was an effective DX antenna but was taken down in favor of a bobtail. The bobtail is a two wire (vertical wires) bobtail so it is not as good as a real bobtail but it is better than the delta loop.
I am hoping that the ZZ will be better than the horizonatl loop. It will certainly solve some logistic problems. The horizontal loop gets in the way of the tiltover tower. So the loop has to be taken down for the tower to tilt over. If the ZZ can replace the horizontal loop it will solve the tower tilt over problem.
The ZZ takes a 65 foot tower. The best I can do is 57 feet. That is to the tippy top part of my auxilliary tilt over mast. The only thing this mast will be supporting is the ZZ loop. The last 12 feet of this tower is one inch aluminum tubing salvaged from an old beam that lost an argument with a tornado.
I figure I can make up for the lack of height by moving the end supports further appart. Got plenty of room to expand to the SE but not sure about the NW. If problems arrise we will linear load the thing until it fits the space allowed.
I probably should have added the following as a comment but here goes anyway.
I finally got the antenna up and running. It is running along with the horizontal loop. I left the horizontal loop up for comparison. Both antennas are tuned to the same part of the 75 meter band. One with a homebrew tuner, the other with an old KW transmatch. Antennas selectable through a large rotary switch. This setup provides instant comparison.
I have been playing around with these two loops on receive only so far. It appears that the new loop is about two S units better on receive on some stations with no effect on others.
I had originally intended to use some surplus RG-62 coax for wire. The coax turned out to be too heavy for the mast. The upper 12 feet of the mast is one inch aluminum tubing and was too weak to really support the weight of 140 feet of coax cable. It was replaced with normal stranded antenna wire which worked fine.
The lower part of the loop is supported by the 2.5 inch pipe section of the mast and coax worked out fine for that run.
Final dimensions were a height of 56 feet with the ends at 9 feet. I had to build a support out of cedar 4x4s to elevate the SE end to 9 feet. The antenna is just like the ZZ Wave Net but installed 9 feet lower than recommended.
This morning (Nov 29, 2009) I had my first schedule with my usual buddy on 75 meters. The new antenna is working fine. The old loop gets me an S7 or so but the new loop gets me 10db over nine.
He was amazed at the difference between the two antennas.
Just finished taking down the old horizontal loop. Don’t need an S7 signal when I can get 10over9 on the new loop.