Propagation News – 20 August 2023

Sunspot activity continues as we head towards solar maximum. We have had a reasonably settled Sun over the past week. The Kp index never exceeded 3.33 and was generally in the ones and twos all week. We also had no M or X-class flares to worry about with only minor C-class events occurring.

The solar flux index stayed in the 140s and 150s, only topping out at 160 on Wednesday and Thursday.

So, it was not a bad week for HF propagation as we head towards the end of August.

There are signs that propagation is improving due to the seasonal change in the chemistry of the F2 layer. With a move towards more monoatomic species and fewer diatomic ones, it means that it is becoming easier to ionise.

Daytime critical frequencies are currently around 6 to 7MHz according to the Dourbes Digisonde, giving a maximum usable frequency over 3,000km of between 18 and 21MHz. 28MHz. Sporadic E contacts have all but finished, but don’t write the 10m band off as you may get the odd surprise.

Twenty metres still seems to be the best DX band this week, according to the Chiltern DX Club, with 17 and 15m also contributing.

FO/F4FJH in French Polynesia; E51JD on the South Cook Islands; and FH4VVK in Mayotte have all been heard on 20m SSB, while 3D2AG in Fiji has been worked on 15m CW.

VHF and up

The fine summer-like weather has returned—at least for this weekend and up to about mid-week—before it becomes more unsettled again. So, tropo will be worth exploring, especially this weekend and during the first part of next week.

Note that in these warmer summer months, tropo is often better overnight and early morning—especially those misty ones—but tends to decay as the ground warms in the morning sunshine. However, coastal paths often remain good throughout the day so tropo paths across the North Sea or English Channel could be worth a look from your holiday deckchair!

The sporadic E season is slowly coming to a close, but it is still worth a check in the evening teatime activity window to make sure nothing is missed, and even better if you can add a morning checkup at around 1030UTC.

The recent Perseids meteor shower may have added some useful meteor debris as fuel, so it is certainly not time to give up checking just yet. However, you may have to manage your expectations on the higher VHF bands.

Meteor scatter is still a good bet in the tail end of the Perseids shower and the usual random meteors increase around dawn. Rain scatter is always an option in the summer months so keep a watch on weather radar displays for the brighter thundery rainfall echoes, especially later next week.

There has been some interesting propagation on 50MHz down to the equatorial belt in the late evenings with D2UY in Angola working FT8 stations in an arc from the Canaries around through northern Scotland, and the whole of the UK to Turkey with ‘Trans-equatorial sounding’ fading patterns, making decodes difficult sometimes.

Moon declination goes negative again this Sunday, shortening Moon visibility windows and—as we are past apogee—path losses will fall all week. 144MHz sky noise is low to moderate until next Friday, peaking at 2900 Kelvin on Saturday morning.

Category: GB2RS Propagation News