I have been looking around for a suitable site for testing antennas using WSPRlite and DXplorer. I wanted somewhere that I could use a reference antenna and an antenna-under-test. The site needed to be flat and unobstructed. I have now found such a site so the first test is to see how two identical antenna perform. Thanks to David Moss for the use of his field. I can see some interesting testing ahead.

It's always tempting to dive in and start doing interesting tests right away but I think that it's important to test the suitability of the site itself first. To do this I set up two identical small transmitting loop antennas about 20 metres apart. They were orientated to that they sat in the nulls of each antenna. Identical WSPRlites were used, together with the new synchronous transmitting and recording system such that only reports taken at the same instant were used in the analysis. The system was left running for approximately 6 hours. The 30m band was used.

Results

Automatic antenna analysis from DXplorer.net

N=353, Mean = 0.56 dB STD = 2.4 dB

Discussion

The results are slightly skewed making analysis difficult. The Mode is 1 dB. The mean is probably not useful given the skewness. However the results give cause for optimisim given:

• the WSPRlites are matched  in power typically to around 0.3 dB
• the antennas were not as precisely oriented as they could (should) have been
• the antenna shapes were subtly different.

Conclusion

While more calibration tests should be done, this initial test gives cause for optimism that with care, accurate antenna measurements can be made.

[Revised 9-May-2017]