Let's try to beat the Yagi!

Yes folks, I may have many faults.  But lack of dedication to the cause is not one of them!

Though it's difficult to make the time at the moment, I did manage a brief visit to a beach with a clear sea horizon from NNE to SSE this evening, to see how well a 1/4 wave vertical, using WSPR, would compare with my 12m LFA aimed at Scandinavia.  I was glad to find some tourists again take an interest in what I was doing; this is a very good way to promote radio if you explain things in a lively, jovial manner.

Looking east, towards Scandinavia, from IO73

The sea is a fair way out but the tide was flooding.  The sand, as is typical on very shallow beaches like this, is permanently saturated with seawater when the tide is out; you can actually see the water break the surface to the right of my rig box and backpack. I know from lots of earlier work that this acts to reduce ground losses pretty much as well as if the water were at the antenna's base.  Modellers always get it wrong, in that they treat a beach as though it is perfectly dry land, a bit like rock or concrete, and then have a sharp dividing line between its poor characteristics and the sea's much better traits.  The reality is very different.

Location (IO73ui) of beach operations.  Lines indicate limits of clear view (north at top).

Relative position of antennas. Yagi just to the south of the Parys Mountain label, vertical on beach at Lligwy Beach label.  Image: Google Earth.

So, how did it go?  Well, Es is of course the dominant mode at the moment.  Closer stations in Denmark were coming in at a tpyical 5dB better to the Yagi, compared to my vertical.  Better by about 4dB than when I took the vertical to the copper mine hill.

Beaming Scandinavia - at considerable expense, effort and visual impact.

But there were three stations at greater distances that produced remarkable results.  Remember, there aren't many stations active on 12m WSPR, and beaming a specific direction means there are even fewer.  Robust results would need a long period of study, but these are pretty reliable, all the same.

SM2LTA came in at -22dB to my 3-ele Yagi.  In the vertical on the beach - wait for it...-5dB!  A 17dB advantage to the vertical!

OH6BG produced an 8dB better signal in the vertical than the Yagi.

LA3JJ heard my 1W at 6dB stronger than the Yagi. 

There's no doubt that, at and beyond 1000km, the enhancement from the beach location can be very strong.  The explanation is definitely ultra-low arrival and departure angles that are inaccessible to the Yagi.

We can see this in action with standard models built into MMANA-GAL. First, the Yagi on my estimated ground conditions, 10m above that ground (most of us can't manage much higher than this, certainly in the UK):

If you plug-in perfect ground conditions (below), there is no practical difference - the peak gain (which is at 30 degrees elevation) - is only 0.3dB greater.  In both cases, you can see that by the time we get to 5 degrees above the horizon, the gain over an isotropic radiator has fallen to the -10dB ring, which is therefore a realised gain of just 2dBi.  Anything that renders the ground ahead of the antenna less than perfectly flat will reduce the low angle gain even further.

But don't get hung-up (great tune!) on the gain at 5 degrees elevation, because this isn't very low at all!  1 degree is a good place to start talking about 'low' angles, by which time the Yagi's pattern line is intersecting, approximately, the -25dB arc, or about minus 12dBi gain overall.

It's easy to see how this all plays out in favour of the vertical, when we look at its (vertically polarised) pattern over seawater:

The gain peaks at ultra-low angles, giving plus 6.65dBi all the way down to the horizon line.  If we add 6.65dB to the negative gain of the Yagi at these elevations, then we get up to around 18dB - which is the gain seen in reality with the case of SM2LTA. Possibly a simplistic analysis, but the general picture is not far from the truth.

Well, I'm glad I did that experiment.  Not that everyone will accept the results.  In recent correspondence, I see such idiotic nonsense as "yes, but not everyone lives near the sea", which is like saying you shouldn't use a car if you happen to have one, because not everyone does.  If I live near the sea, I can - and will - take advantage of it.  I hope others reading this will, too, because you get world-class performance from little more than junk wire!