Friday, 10 February 2017

Homebrew Magloop vs. Butternut Vertical, and Others.

Thanks to a rare spell of cold, fairly calm and, above all, dry winter weather this week, I've had a chance to stick my magloop out in the garden attached to my WSPRlite unit at 200mW out.

I'm amazed that the WSPRlite is able to handle the sub-zero temperatures, all without a hint of drift.  That said, someone from Norway is running his at -17 degrees Celsius, so it's clearly a very robust unit!

On initial assessment, it looked as though my magloop wasn't doing terribly well, because the reach of the signal was only really as far as the Canary Islands.  But I then started comparing my results against other stations, using the very useful DXplorer webware.  This showed that it wasn't the antenna, but poor propagation conditions that was the cause of the short reach.

This comparison revealed, again and again, a magloop that was doing almost as well as, and sometimes better than, full-sized antennas like the Butternut vertical operated by G0MJW, a plot for which is given below.  The only time it does poorly is during the later evening, apparently a result of having a low elevation pattern (not detecting high angle, short skip signals).

The only thing to do now is build-up the data and see how things pan out over time.

For sure, those who say that magloops are of no use are definitely wrong!  Also nice to remember that my magloop,even with new 28mm copper tube, cost only about £40, when the Butternut is several hundred pounds!


Encouraged by the surprisingly good performance of my loop, I set things up for 30m the following day, where propagation was considerably better.

I compared my loop with known antennas - G3CWI running a doublet, and G7TSX running an inverted-L.

Again, the results were excellent.  Indeed, over the 1-day run, which I accept needs lengthening (the run is still ongoing), the magloop in this environment beats the socks off the doublet in its environment on both mean and maximum distances spotted.  For the inverted-L, my loop is essentially the same on the mean distance, and very slightly behind on maximum distance.  Remember my loop is just 1.5m off the ground, and only 1.2m per side!

My loop (blue) vs. a doublet (red)

My loop vs. an inverted-L.

I've no doubt that, if I were to run a doublet and/or inverted-L in the same location as my loop, it would be a little behind in comparison.  But there's the rub - from the right location, a magloop can indeed be as good as and even better than a full-sized wire antenna in a somewhat less ideal location.

So, the main message is: don't take what others say about any particular antenna as Gospel, because they know nothing about your environment, and are probably ignoring or underestimating the effect of theirs!

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