Tag Archives: megaloop

MegaLoop Antenna

XXT Meage LoopI’m currently writing an article outlining the characteristics of the Mega Loop antenna we use for Dorridge Scouts. If you would like a preview of this white-paper, please let me know.

The XXT Mega Loop is the name given for the application of a horizontally mounted delta-loop that has known gain dependant on wavelength size and height above ground.

At quarter wavelength above ground and above, Mega-Loops start exhibiting gain that is proportional to its wavelength and height. A whole series of articles is currently being written by the author, however for the time being, these few articles may help you determine how we operate the Mega-Loop at Dorridge Scout Group HQ.

Firing supports over trees:

The 160m Loop

GB1DSG Special Event Mega Loop Project

Aidan M6TTT

Picture shows Aidan, M6TTT running his first pile-up from the Hut. First class Aidan, you really got the swing of this on Sunday. Fabulous effort.

We put nearly 800 QSOs (contacts) in the log and there are so many highlights, I can’t begin to mention them all. My personal highlight was working VK3FT at lunchtime today with a land-line quality copy on the 20 meter band. Keith spotted us which probably accounted for flurry of VK stations immediately afterwards from Australia. Thanks Keith.

We got spotted 25 times over the weekend which is certainly our personal record. Thanks to those stations that helped us maintain the pile up!

As usual, we used the MegaLoop (delta-loop) antenna, see this page for details:

Cheers all!

Callum.

How to build a proper Skyloop (Delta loop construction)

Well folks, I’ve been continuing my experiments with my two sky loops (closed loops of wire held above the ground at three or more points) and comparing them against various verticals. Sometimes the verticals win, other times the loops do. I’ve had 8m verticals and longer too. Today, I’ve put the 12m vertical back up (https://www.m0mcx.co.uk/?p=102) fed with my trusty SG230 coupler. I may add that anyone interested in fast antenna experiments should get one of these. A tremendous piece of kit. Matches anything.

SkyloopApart from the noise factor (loops are quiet), the vertical seems to make a better impact on transmit more often than not for DX, unless I’m into NVIS or near NVIS (500 miles or so). Even then, up to 1,500 miles, the jury is out – either antenna can win. Beyond 1,500 miles the vertical seems to do a better job most of the time – not always, however my loops are very low to the ground, maximum height of 7 meters. On 40m, I would say the vertical is a better antenna to have almost all of the time unless you need NVIS for local copying – and with the sun spot cycle as it is, you won’t get this for a while yet!

I used to have the opinion that loops were more often than not, cloud warmers. However let’s face it, so are almost all low-to-the-ground HF antennas. My interest was tickled recently when VE7HA mailed me an MMANA file of a very high (80- foot) 300 foot circumference skyloop that he had built with three very large trees. He claimed great contest results with this loop. I had a look at the plots. Yes, he was right.. Check this out, 10.4 dbi gain at 5 degrees to the horizon on 10m? On 15m band, we’re looking at 12.5 dbi at 7 degrees to horizon! On 20, it’s as good with 10.5 dbi gain at less than 10 degrees.

Skyloop Far Field PlotNow.. This is a very different animal to the Skyloops that most people build. If you want a pile-up generator, this is the animal to have. It fundamentally, takes all your RF energy and pancakes it low to the ground in various star shapes. Very Of course, you will sometimes null out the station you want but you could get really clever and change feedpoints with relays. But ignoring the clever engineering, this has changed my mind as to the effectiveness of a high skyloop.

Be prepared to get into some matching territory though, ideally an automatic coupler at the fedpoint with open wire feeder, or perhaps an olde-fashioned tuner in the shack!

Some day I will build one, I just don’t have the trees :(

(Years later: I did build one. They’re amazing).

73

Callum.