Would it be possible to take half of your formula to make a 40/20/10 meter loop?

And Also GREAT!!!! Instructions

Every antenna is compromised to be able to be used as a multi-band antenna with the exception of normal harmonics. With that said let’s make our antenna resonant at 7.30 MHz (40 meters) and this will also be an 80 meter antenna resonant at 3.65 MHz As you can see, we are at one end of the 40 meter band and the other end of the 80 meter band (a compromise), but will play very well on both bands.

The 450 ohm ladder-line stub is going to be ¼ wavelength of the 80 meter band. Which is also going to shorten a normal 80 meter loop by the same length so that we end up with a full wavelength.

Stub – 234/3.65 = 64.1 feet (64 feet is close enough) so we cut the 450 ohm ladder-line to a length of 32 feet… (32 feet X 2 wires = 64 feet). Solder both wires of one end together.

80 meter loop is 1005/3.65 = 275.34 feet less the ¼ wave-length of 64 feet gives us 211.34 feet (211 feet is close enough).

So our antenna wire is 211 feet and the 450 ohm stub is 32 feet long. Now we cut the 211 feet of wire in half and attach one wire of the 32 foot 450 ohm ladder-line to each ½ of the 211 foot (105.5 foot leg). Then solder the other ends of the 450 ohm ladder-line together – if you have not already done so as mentioned above. Now from one end of the loop to the other end we have a length of 275 feet.

Some say to put a 4:1 balun at the feed point and this is fine however a preferred way to feed any loop is with a “Q-section”. Without the details of the formula, the length of a “Q-section” for 80 meters is about 41 feet and 20.5 feet for 40 meters. We build our “Q-section” using 75 ohm coax. (You can use the 75 ohm coax that is used for your cable TV or satellite). I have used this with over 600 watts with no failures. So we cut our 75 ohm coax to 41 feet and attach it to our loop (dialect to one leg and shield to the other leg), and add a coax connector to the other end.

Now we just use a barrel connector to connect two PL-259′s and then attach the 50 ohm coax to the 75 ohm coax… By using a “Q-section” we are more confident that while tuning our antenna we are not just tuning the balun…. This is some food for thought for those that use baluns.

You can add an air choke to the feed line by taking a large plastic coffee can and wrapping about 8-12 turns around the can… Or take and wrap about 19 feet of coax around 4” PVC pipe.

Summary – 211 feet for the loop, 32 feet for the stub, 41 feet of 75 ohm coax for the “Q-section”….

To tune the antenna you would do either the trimming of the stub or the antenna itself remember if you trim the antenna then you have two sides – so if you add/subtract 4 feet then 2 feet each side of the stub, or 2 feet off of the stub…. etc… Good luck and many contacts…

The new version I made was using a plastic coated multi strand copper wire – the wire used was classed here in Australia as a 30 amp cable – it has 52 strands and the copper section is 2mm dia – quite heavy wire for antennas, but worthwhile for longevity …. The ladder line section is homebrew of the same wire, with a 50mm spacing. I also run it through a homebrew 4:1 Air Balun that I found plans for on the net – made using twin core wire (figure8) wound on to a 50mm PVC section. Very easy and functional.

The SuperLoop now resides permanantly by way of a 8mm Silver Nylon rope strung up between 2 very tall Pine trees – the loop is attached to the rope with cable ties every meter and the corners of the loop are helped make the transition to the apex by using 2 small (50mm) lengths of PVC 50mm dia, cable tied as well (stops making to sharp a corner for the wire) …

I constantly get unbiased signal reports on 80m + 40m, and am exceptionally pleased with this antenna – I have set up the antenna to be resonant at 3.585MHz and use no tuner for operation here in Australia. I do use a tuner on 40m, 20m, 15m, 10m + 6m bands, with good results on ALL bands.

Talk about Bang for your Buck, this antenna is a brilliant design and have worked many stations all over Europe on 40m 20m etc …. using 100w. I can’t speak to highly of this antenna – Many thanks to Dr. Ace for his website where I found the design. I have told many operators of the design and a few have built them and are getting good results as well.

Not convinced – well all I can say is, BUILD one and try it for yourself – you won’t be dissapointed.

Cheers to ALL – 73
Greg – VK2MTC