More data from the beach.

Yesterday was another lovely sunny day, albeit with a steady 30 knot wind blowing from the south.  A good day for more beach WSPR work, using my daughter's callsign.

Dying days of summer.  Rhosneigr beach, Anglesey (IO73rf).  Note 1/4 and 1/2 wave markers in sand!

There are still a fair number of tourists around, who tend to pose occasional problems in terms of managing adult, child and dog safety near the antenna.  Luckily, the stiff wind had kept all but a small number away from the seaside!

The beach I used has a very wide open aspect from SSW to NNW - Rhosneigr Beach, on the west coast of Anglesey.  This is much easier to work from than Newborough, my previous site, as it has a steeper slope, with no need to move the antenna for over two hours.

Operating site.

I started work at low tide, but the water's edge hardly moved during the first two hours, as the water on the incoming tide simply filled a depression in the beach; very useful!  The antenna was at just over 1/2 a wavelength from the water's edge at its furthest point, and 1/4 wavelength as I neared the end of the run.

Now I'll turn some attention to that working distance first.  Just about anybody who writes about working at the seaside will conclude that you have to be within 1/4 of a wavelength to see the enhancement effects of the water.  They claim that useful gain due to the water is lost beyond 1/2 a wavelength.  A lot of the claims are based on American computer modelling, and not on real world operating.  Those models use a flawed version of reality, where there is something called 'sea' that stops at a single, discrete point, and everything beyond that is termed 'land'.

The reality it very different at the beaches I work from: the water's edge may be so-and-so metres away from you, but on a gently sloping sandy beach, the sand remains fully saturated with seawater,which is often a mix of slowly percolating water left behind as the tide goes out, and upward migrating water from the water 'table' just below the surface.  If you cut a hole in the sand, it immediately fills with water all the way to the sandy surface.

So, in my situation, whilst the antenna seemed initially to be physically away from the sea/land interface it was, electrically, still positioned directly over seawater, which also extended to the landward side.  You can actually see this in the photo above, as the large rock embedded in the sand is surrounded with seawater; it's not a pool as such, because the sand is permeable, and the water would otherwise quickly seep out. 

This reasoning, and its expectations, is supported by a couple of plots I prepared for two stations.  You can see that, even though the tide was advancing very slowly towards the antenna, decreasing from just over 1/2 to 1/4 wave with time, there is no evident enhancement due to the water's edge itself getting closer:

As for the results, well, they were very pleasing, with up to +17dB available, over and above G0CCL, a very reliable and efficient station in Cambridgeshire, which alternates between 1 and 5W output, for which allowance is made in the computations:

So, at the highest enhancement level, you could set 1W on your transceiver and enjoy an effective output of 50W.  Now that's worth going down the beach and getting covered in wet, sticky sand!

Very interestingly, when I looked at a couple of German stations lying to landward (east), my beachside location yielded a 26dB enhancement for DL1DAF, and 29.5dB for DF5FH, relative to G0CCL.  I don't know what the actual mechanism for this very large enhancement to the landward side may be.

When I tried to run a comparison with the only other 100mW station I could find (G4SGI) on SOTABeams' DXPlorer site, it was impossible to do, because G4SGI's signal never made it further than 1010 km!  Unfortunately, DXPlorer doesn't currently make automated, output-compensated computations between stations; I've suggested that such a column in their tables should be included.

14MHz, 0.1W WSPR coverage over ~2.5 hours from IO73rf.