WSPR Antenna Comparison

Having recently raised a Off-Center Fed Dipole, and figured out how to use WSPR with my FT-991, I thought it would be interesting to compare the OCFD with my 35′ End Fed Wire.

Getting WSJT-X to work with the FT-991 was a bit of a challenge, but I mostly blame the Glenmorangie. Some handy links I used during that discovery were Andre Le Roux’ page on setting up WSJT-X with the FT-991, and N1RWY’s setup notes page. (Also see N1RWY’s updated page here). These proved very useful, so huge appreciation to them for their hard work! The main stumbling block for me was having my FT-991 on “PSK” data mode, from earlier experiments with PSK31. WSPR won’t work unless you change that to “OTHERS”.

For my test, I ran WSJT-X for 10 minutes with each antenna, keeping logs, taking screenshots of the waterfall display in WSJT-X, and checking my results on the WSPRnet map page.

The following image is the waterfall display while using the End Fed, then changing over to the Dipole. Read it from the bottom up (most recent time at top).

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Spectrum Scope Waterfall Display Comparison

You can see that there is a significant increase in both the signal strength, and the number of signals received when using the OCFD. Adding the maps from WSPRnet illustrate this also:

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Spectrum Scope Waterfall Display & Maps Comparison

Here is the 10 minute contact log when using the End Fed Wire Antenna:

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And, here is the 10 minute contact log when using the Off-Center Fed Dipole:

Click to Enlarge

Of course, propagation changes over time (which is why I only gave them a short 10 minute test each), and these results aren’t very scientific, but there is a clear difference between the two. DX performance of the OCFD seems far superior to the End Fed.

Local, ground wave propagation may well be completely different to my End Fed antenna. I guess I’ll have to wait until the local HF nets happen to find out.

The OCFD sits at about 20-25 feet currently, strung between two trees, but I’m hoping to get it higher eventually, with some help from a drone magician. 🙂

Edit: I left it running while I wrote this blog post, and got quite a few more!

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AD5GG works in the real world as an RF design engineer. Occasionally, he posts articles on this very site. Sometimes they're even worth reading. Please feel free to comment on posts using the comment system at the end of each post, and use the discussion forum.

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