My antenna is hardly world-class in terms of design. Just a 1/4 wave for 40m hanging off and fed against my 6m-high tower with a 12m Yagi on top. It was a throw-up job one day that proved to be a really good antenna. More importantly, it's entirely hurricane-resistant - a major consideration up here.
Whilst the set-up is modest, it turns out to be perfect for this elevated position overlooking the Irish Sea. The ARRL's HFTA terrain analysis tool shows that low horizontal antennas are in fact preferable at this location, due to the steeply sloping ground profile affording considerable gain, especially towards the western hemisphere of the local, sea horizon. For example, peak gain for a 20m horizontal dipole at 2 degrees elevation arises at a dipole height of just 3m.
The associated, DXPlorer web-based analysis tool, which is also sold (for £19.95 per year) on a subscription basis by SOTABeams, is an easy way to look in detail at what happens to your transmitted signal with time. More importantly still, it allows you to easily compare your graph of spots against any other operator on the same band.
Already, DXPlorer is allowing me to prove what I've known for years - that my QTH permits access to extremely low angles, and that this gives rise to some outstanding DX performance. This is especially so when the ground is extremely highly mineralised (it's an old copper mine!)
Here's the latest output for 200mW on 40m over about 5 days. I've chosen G8LIK because he gets a very high number of spots and appears to have a reasonably open aspect, free of too much development around his antenna.
If we take a slice of just one day through that data, we can see in more detail what's going on.
On the left hand side of the 1-day plot, which tends to repeat every day, is near-identical performance, with me slightly ahead in terms of reported distance, during the late morning, afternoon and into the early evening (ca. 19:00UT).
From early evening onwards, things change very dramatically indeed. By 21:00UT, G8LIK is reporting only receiving stations within a couple of hundred kilometres, whilst I'm being heard across the Atlantic.
Around midnight, our two stations are more or less equal for an hour or so. From then until 06:20UT, G8LIK drops away to being heard only by local stations, whilst I continue to be heard across the Atlantic throughout the early morning hours.
There's then a huge departure again between about 08:00 and 10:30 UT, where distances for me are about 5 times better than the other station, before we both come more or less together again for the later morning.
Whilst there are occasional differences in the detail, the general picture is quite steadily repeated each day, and is much the same when the comparison is with other stations. Here, for example, is another well-spotted station, M0VGA:
I should point out, for those of a more gung-ho attitude, that I have chosen these two stations for comparison not in order to denigrate them, but because they are amongst the best 40m WSPR stations around. It's clear that my results are not the result of some incredible knowledge or ability, but the result of a well-made and well-chosen antenna, installed at a very good location with exceptional, bordering on unique ground.
I'm very grateful for WSPRlite and DXPlorer, because when I come to put this place on the market, I will be able to objectively back-up my claims that this is a QTH worth having.
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