Saturday, May 16, 2020

Extending The Arctic MW DX Season Into The Midnight Sun

May 15. At around 18:30 UTC, ABC Newsradio, Busselton WA 1152, with a readable signal. Distance: 13,396 km. On the following night, the sun did not set. Now, how is that for daytime reception?

Our beverages shouldn't even be up at this time of year. The thing is, I need to adjust antenna deployment to reindeer migration. Sounds exotic, doesn't it. Well, there is a logic behind this. The reindeer have their summer pastures at the coast. As autumn comes, they migrate to the inland winter pastures. Around August 25 or so, the area is "clear" for antenna deployment. For obvious reasons, I don't want the animals to have their antlers entangled in our wires. It's not good for the wires, and certainly not for the reindeer. One year, a lonely left-behinder I wasn't aware of got trapped in the 310 beverage wire. I managed to free the animal, though it was a bit scary since it was a full-grown oxen with impressive antlers!

When April arrives, the season is more or less over, and the beverages are reeled in, leaving the area safe for the original "inhabitants" to enter. However, the 80-degrees beverage was left standing this year, because of excessive snow levels on the path. Not much trouble for the reindeer though, they can jump over the visible parts of the wire.

This year, we started to monitor the beverage more closely than previous years since we heard good signals from Australia late in April So, for how long? As it turned out, for a very long time.

There is no sunset from May 16 onwards, and I was quite surprised to hear Adelaide-891 and Wagin (WA) 1296 in the end of April, when midnight was only civil twilight. Adelaide, and even other stations like 5AU on 1242, were heard on May 2. And the following days, until May 15 at least, stations from Western Australia were heard. And maybe we could have heard them even longer if conditioins were right. How could this be?

There are two reasons. First, and definitely most important: Mainland Asia, and especially China, are significantly attenuated at this time of the year. So, even a very weak signal can be copied. Secondly, there is greyline propagation from Australia almost all the way. Only the last few hundred km do the signal propagate through daylight, and then with the sun at a very low azimuth. And daylight reception of distant MW stations is nothing new in the Arctic. It is quite common to log North American stations in bright sunshine during autumn and spring here.

ABC Adelaide 891 at 18:30 UTC on May 5.
Interestingly, the signal from Adelaide crosses China with all their power houses which are not heard at all. As daytime increases, only the westernmost stations in Australia are audible. Such as 1152, 1269 and 1296.

In all fairness, this is not exciting DX, in that one could hope to hear new stations. Still, for us, it's a new barrier being broken. MW DX from 13,000+ km away, while in 24-hour daylight!