Long distance VHF and UHF signal propagation caused by ducting #hamradio

On the 5th and 6th of June 2016 we had exceptional VHF and UHF signal propagation in our area, I had several QSO’s with stations in the United Kingdom and also heard stations from Germany. The repeater system PI2NOS was very noisy at times because of the cross-channel repeater interference. With a 5 Watt hand held transceiver I was able to open the PI2NON repeater from a hill just north of Rotterdam, this means that you can go over your horizon which is normally the limit for VHF and UHF frequencies used by radio amateurs. I logged some calls on QRZ.com which I normally don’t log with the 2m and 70cm contacts. I had a QSO with Eddie, MM0MUN who lives in Aberdeen which is 714km to our NNW. How this is possible is not clear to me, perhaps propagation went via the Ipswich repeater (GB3PO) on 145.650 MHz. If someone keeps a log there then it may be interesting to find out.

ducting_5and6jun2016

To measure the propagation effect I decided to leave WSPR on last night, here is the map that I found over the last 6 hours (it is now 7:35AM on 6-June-2016). The map shows contacts deep into the UK and surprisingly enough also into Denmark. The map shows all contacts that have been established on the 2 meter WSPR frequency.

Long distance VHF and UHF connections can only be explained by a phenomenon called ducting where radio signals are not following a straight path because of refraction. The weather conditions should help, there should be a temperature inversion. The Dutch weather radar (via buienradar.nl) did pick up scatter over the north sea area while we have blue sky weather. This suggests that there may be a cold patch of air under a warmer top layer which is what an temperature inversion is.

Propagation maps for 2m can be found here.

73 from Ernst PA1EJO, last update: 6-June-2016

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