Saturday, 5 May 2018

Reflections on a reflector.

WSPR operations continue apace at the Copper Mountain station!

With the winter winds gone for a while, and good conditions across to the western US, I decided to throw up a reflector for my 20m delta.  The spacing between elements is exactly 5m, or a 1/4 wave at 14MHz.  This was simply because it favoured fixing a post at that point.  The ideal spacing is more like 3.5 to 4m.

I did this many years ago, but didn't really get around to using WSPR.

Beaming the USA (reflector at right).
I seem to have run out of good wire these days, so some very lightweight equipment wire bits were soldered together, amounting to a total of 23m.  The light weight of the wire was actually a benefit, as I had to use every last mm of the top, weak section of an elderly 10m fishing pole - which are usually a bit shorter than this - to support it at the correct height.

A quick look with the SARK analyser showed the system was very well behaved, at 1.28:1 SWR at the WSPR frequency:

A walk around what is now a two element vertically polarised 'quad' system confirmed the modelled expectation of modest front to back ratio, the rear lobe being very clearly 'seen' in my simple RF meter.

Generalised, but accurate azimuth pattern for a 2 ele loop system.

How did it work out?  Well, conditions on 14MHz were quite poor due to a situation where a very strong sporadic E propagation was present across HF and into VHF.  This was strongly inhibiting propagation across the Atlantic for most users.

I found very many stations were unique in being heard by my 2 ele loop system.  There were enough of these, a few of which I present as independent evidence below, to conclude that the system works exceptionally well.  Even into the early morning, when west coast US stations would not be expected to be reaching the EU at 14MHz under those propagation conditions, I was hearing a couple out in the far western coasts of America.

K7KRR unique spot in the hour (evening of May 04, 2018)
K6MCS, a highly unusual spot for the early-to-mid morning period in the UK.

VE3XIX, unique spot in the hour (evening of May 04, 2018)
WA1DLZ, heard only by me and the globally-number 1WSPR RX station, EA8BFK.  Morning of May 05, 2018.

AE7YQ, hour to 15:25UT, 05/5/2018.

Very curiously, AA7FV wasn't coming through quite as often or as strongly as previous nights.  It may well be that either propagation conditions didn't favour the path or, more likely, that my beam was slightly less than ideal for him. 

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