Tuesday, 7 February 2017

WSPRlite 200mW - The Results

This is more a diary entry for my records than anything of interest to readers, but it might be of use, nonetheless.

For just under a week, I've run WSPRlite at 200mW output into a vertical delta loop antenna, fed by 300 Ohm twin via a 6:1 balun.

The comparison station - G7CKX - has been chosen as one of the best-heard by others, and running the same power as me.  I've carefully gone through many stations and contacted operators about antenna details.  It's clear that the overall pattern shown by the comparison station is entirely representative of what all other stations running the same power with simple antennas showed.  In some cases, my antenna matched the distances achieved by others running up to 5W (a 14dB greater output.)

The first obvious difference is that, in this case and for all others consulted, there is a considerable difference, in my favour, in both average (+6.4% of possible) and maximum (+10.3% of maximum) distances reached.

Secondly, it's clear that my vertical loop acts in an extremely consistent way from day to day.  There's a sharp rise as the ionosphere is lit, a small step in the morning, and then a steep climb to a very steady peak distance for some hours prior to the band closing even more sharply in the mid-evening (February 2017).

The other antenna, which seems characteristic of a dipole, shows distinct peaks and troughs which are not present in my vertical antenna.  This probably reflects the directionality of a dipole, and may also highlight some elevation pattern changes, evident as the day progresses.

What is clear is that my delta loop performs very well indeed and, at last, I have some objective data with which to back this claim up.  The overwhelmingly important factors are a superb ground (an old copper mine) and an undeveloped, elevated position overlooking the sea. 

The real lesson for others reading this is: don't necessarily accept what others tell you about how and why antennas perform.  Exactly what you will get out of any given antenna depends very critically on the environment - something that the majority of urban-prone operators simply fail - and often refuse - to accept.

For interest, this is the plot of people hearing both stations mentioned above:

MW1CFN (blue), G7CKX (red), both (green)  Apologies to the colour 'blind'!

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