WSPR Around The World.

WSPR is one of those things that I kept coming across, but knew little about.  In fact, I had no idea other than it was some kind of beacon mode, and I knew nothing about those, either.

Then, one day, the penny dropped.  I was looking into JT65, another weak signal digital mode, and then came across WSPR in the same software package known as WSJT.  For WSPR, though, I use the standalone package for that mode, known simply as WSPR (free).

Screen shot, showing WSPR signal waterfall.

The main problem at this station for some time has been the lack of a proper digital interface.  I decided last week that enough was enough, and took the plunge with Neil, G4ZLP's USB interface, which really is hand made, and got me running on all the digital modes in less than 25 minutes from opening the box and having no previous digital experience at all.

The only problem I did come across was signal stability, which is very demanding for digital modes - just +/- 1Hz is the ideal, and beyond 4Hz, the software will struggle to decode the signal.  My TS480 is pretty stable, but only if it doesn't run too hot or cold; it needs to settle down into an undemanding routine of sending some, listening more (which is how WSPR is meant to work, anyway).  It's changes in the crystal temperature that are the problem, not which temperature it's at per se.  Too much on and offing of the cooling fan introduces big swings in the stability of the reference crystal; I won't be forking out even more money for a temperature-compensated one, which is anyway not perfect.  In practice, swings of +/-3Hz don't seem to affect the received coverage much, but I now have it down to about -1Hz, which is more than acceptable, given the equipment.

Getting out on 20 metres and above is no problem; a multiband, 4:1-fed delta loop cut nominally for 20m works a treat.  But 30 and more especially 40m were not so good, as I had to rely on an end-fed vertical that struggled to get out well on low power, and it is a very noisy antenna on 40m.

The spark of inspiration then hit me.  All those hours of reading antenna literature paid off.  If I can't and don't want to put up a 20m-long dipole for 40m, why not put up a half-delta loop?  This is just 1/6 wave high - an old and partly broken fishing/crappie/squid pole does the job for me - and 1/3 wave as a sloping horizontal section to the ground.  The antenna is grounded into copper water pipe sections driven into our superb ground, fed with coax into a balun or other common-mode busting device.

That's all there is too it.  Earth connections are to copper pipes or rods that provides the other half of the antenna, but use a 1:1 balun or ferrites for the coax!

We all know about antenna images, but it all seems somehow unlikely, somehow unreal.  But I can tell you that reality proves the theory!  Within a few minutes, my 4W signal was reaching Australia during the evening - something I could only dream about with my vertical on 40m.  The noise level for the band has crashed, and now I can clearly hear real 40m SSB DX signals from antipodean points.  Over the next few days, I'll try to talk to them, as well!

So there you go.  Full delta loop performance, with low-angle DX pattern for 40m (matches up on higher bands, too), for half the wire, half the space, and no stupidly-tall vertical structures to contend with.  Who couldn't do with an antenna like that?