Horizontal on the mountain

After an interesting outing onto the local copper mine recently, I decided to try something a bit more horizontally-polarised for once.

I say 'a bit', because putting up a flat-top dipole is so difficult as to render it entirely impractical for /P deployment.  So, instead, I used a shallow-sloping dipole, cut for the lower end of 14MHz (resonant at just under 14.0MHz in practice).

Nice and warm on the hill.

 

Even putting up a sloping dipole is, though, a lot more hassle than a 1/4 wave vertical, bordering on the impractical.  The string necessary to open-out the dipole arms mean that the extent of the set-up spans something like 15m on each side of the support.  Not so good if in a place where there are a lot of people moving about (EURAO provides 9 million Euro public liability insurance for just 10 Euro annual membership - you would be silly not to take advantage of this important provision).

The support itself, a ~9m fibreglass pole, is very wind-prone, and needs a strong base support; in my case, I had to take a 'L' section steel and hammer it into one of the few places on a rocky hill that this can be done.

And then there is the local population of snakes to take into account when dancing around the dense heather!  

After all that trouble, I ran the dipole facing NW/SE, and then N/S on WSPR, comparing to my vertical delta loop, just ~500m away, but lower down the hill.

Results were good.  Out of 11 stations I used for the comparison on receive, no less than 6 (within the dipole beaming direction) were not heard at all by my delta.  It can be implied, from the strength seen at the dipole that did hear those stations, that the difference in signal for some was as high as 20dB; e.g. K5XL was -14dB in the dipole, so not being heard at the loop implies a 20dB difference with a S/N detection limit of ~34dB.  

Of the remaining ones heard, the median enhancement seen by the dipole was +5dB.  

On transmit, six stations in the beaming direction of the dipole produced a median +8.25dB enhancement, relative to the vertical loop.

In the case of both RX and TX, the best enhancements, all in the narrow range of  +10.5 to +13dB, were seen at the longer DX range (typically west coast US/Canada).  Curiously, KFS, in the San Francisco region, heard the dipole 2dB weaker than the vertical delta - the only such example seen. 

The 1/4 wave vertical on the hill, which is infinitely easier and quicker to deploy in the field, yielded an enhancement on received signals of about +9dB, relative to the vertical delta at home.  

View out to sea from slightly further up the hill, on the previous day's outing with a vertical.  Unlike the dipole, the vertical can be easily put up, even on hard rocky ground like this.

 

So it's pretty clear that there is not much point bothering with the considerable hassle of the dipole.   Les Moxon's assertion in his HF Antennas for all Locations book, that an antenna on a hill next to the sea "must" use horizontal polarisation to benefit from ground reflections and so yield the best enhancements, is proven incorrect when we consider overall results.  Of course, there may be exceptions in terms of specific paths to specific stations.