venerdì 9 giugno 2017

Propagation News – 11 June 2017

Last weekend’s National Field Day saw only average HF propagation, with a geomagnetic disturbance on the Saturday evening sending the K-index to four. Nevertheless, there was DX to be had, even if most of it was on 20 metres. G4ARN/P in Norfolk reported working Brazil on 20m using five watts, but the majority of their other contacts were mostly European.

Sporadic E did manage to cause some excitement up to 28MHz, but you had to be in the right place at the right time. The rest of the week was characterised by relatively-settled geomagnetic conditions and a solar flux index in the seventies.

Twenty metres threw up some interesting openings in the evenings. As the sun began to set, D-layer absorption dropped and David, G3YYD reported working the USA, Mexico, Chile, Venezuela, and Barbados on 20m SSB from 2100 to 2330UTC. This backs up what we have been saying about 20m remaining open longer as we head towards the summer.

Next week, the solar flux index is predicted to remain around 78 to 80. Geomagnetic conditions may be good until 14 June, when they may then become unsettled until the 18th. We suggest the best DX may be available this weekend and early next week, with F2 layer openings up to 20m and occasionally 17m.
Sporadic E openings could occur from as low as 80m and up to 10m, although D-layer absorption may hide them on the lower bands during daylight.

VHF and up:

The unsettled weather has lasted into this weekend with further spells of rain or showers. This type of weather is good for rain scatter on the GHz bands, but not much else.

Early next week, high pressure starts to build across southern Britain and is later expected to form a small detached high over the country. This should be good for tropospheric opening prospects, which should improve as the week progresses.

Sporadic E is well under way now, with good QSOs being made, including multi-hop transatlantic and Japanese QSOs on 50MHz. Even small stations are benefitting from the upsurge in digimode activity, but please try to spread out from 50.276MHz and keep to the correct time slot for your direction to avoid QRM. Most of all, please don’t run ‘attended JT beacons’ on this frequency: leave it free for QSOs and calling CQ. Follow the clusters and beacons to get an early advantage and select the late morning and late afternoon prime times for checking the bands from 10m up to 2m.

The openings tend to move across Europe from east to west, so don’t fix your beam in one direction only. This is not the sporadic E patch moving, but different areas becoming active as the earth turns. There is often a lull during early afternoon and move up to the higher bands as they open to get maximum range.

This is another poor week for EME, with negative moon declination and high losses due to the apogee on the 8th, so keep tweaking those systems on sun noise to optimise your performance.