During the big Sporadic E opening on 12th June, I noticed some unusual signals on Band 2. This was only noticeable because I was running an SDR and is more a visual effect than anything else, but it’s not something I’ve ever seen before?
First of all, here is a screenshot of what I would consider to be normal Es signals:
Apart from the large red signal near the centre (RTE R1, at 88.2MHz), almost all the other signals are from Spain, via Es. The signals are fading in and out over time, but look quite ordinary. The VFO is tuned to a station on 88.6MHz with a PI code of E212, and a PS (seen earlier) of RNE-CLAS, i.e. “RNE Radio Clásica, Confrides/Aitana” in locator IM98.
A little earlier this is what the screen looked like, unfortunately slightly clipped by the screen grabber:
Note the strange wishy-washy fading effect, which appears to be extremely frequency-selective. Parts of the *same* radio transmission appear to be fading differently from others, giving a slanted look to the signals. I’m wondering what the propagation effect is that causes this: perhaps some multipathing?