Propagation News – 18 June 2023
We had another week of sound HF propagation, helped by relatively quiet geomagnetic conditions, a lack of bad solar flares, and some good multi-hop Sporadic-E openings.
The Kp index never rose above three and was mostly ones and twos. This was no doubt helped by no M-class or higher solar flares and no Earth-directed coronal mass ejections. A large filament did break away from the Sun on the 12th of June, but luckily it was directed away from Earth.
The solar flux index declined to the mid-140s after reaching 172 on the 6th of June.
Paul, GM4ULS sent in an impressive log of 10m SSB contacts with Brazil, Argentina, Chile and Uruguay. These were mostly during the late afternoon although Paul says the openings often started around noon. F2-layer propagation was the first thought, but closer analysis suggests that these were more likely to be multi-hop Sporadic-E.
If these contacts die out as we progress through the summer that should confirm that they were multi-hop Sporadic-E. Paul does have one tip. He listens to 27.555MHz, which is the SSB CB calling frequency. If he hears activity there he then fires up on the 10m band.
Other DX this week has included VP6A on Ducie Island in the South Pacific. This DXpedition should be active until the 26th of June, so there is still plenty of time to work them. 8Q7KB in the Maldives should also be on until the 21st of June.
Next week, the Space Weather Prediction Centre thinks the Solar Flux Index will start the week at around 150, rising to 170 as the week progresses. After a geomagnetic disturbance this weekend that may see the Kp index rise to four, and is likely caused by a coronal hole on the Sun’s surface, we may expect quieter conditions next week with a maximum Kp index of two.
VHF and up
There has been some excellent Sporadic-E and super Tropo propagation during recent UK Activity Contest events. This is high-season for Sporadic-E, so it’s worth a few notes to sharpen your DX potential.
There are often two main ‘windows’ of activity: mid-morning and late afternoon or early evening.
For early risers there can be a surprise ‘window’ of activity around 0600 to 0700UTC on some days and this is particularly useful for paths across the pole to Japan and the Pacific.
The tendency is for openings to migrate westwards. Paths across eastern Europe will be replaced by new paths to Italy or even Iberia as the particular event ‘window’ migrates west.
In this peak season the Sporadic-E operating ‘windows’ may almost merge into one continuous activity period, especially on the lower bands such as 10m and 6m. As paths to Portugal fade, the new cycle may be starting with paths to Scandinavia and the Baltic.
Multi-hop paths will be weaker than single hop, and often more fleeting due to the complex geometry required, making the slower data modes frustrating. Add this to frequency spreading, and sometimes slick, fast CW can be the best mode if you can find the activity.
The prolonged high pressure has provided some very good Tropo paths, particularly across the North Sea to Scandinavia. This may not be so reliable in the coming week as low pressure moves in and offers heavy thundery showers as a source of rain scatter for GHz operators.
Meteor scatter and aurora are always possible, but Sporadic-E will probably be too much of a distraction.
Sunday sees peak Moon declination but with apogee this coming Thursday, path losses will be at their highest.
144MHz sky noise is moderate until Saturday afternoon when the Sun and Moon are very close in the sky, spoiling the weekend for VHF EME. This “close to eclipse” condition persists until Sunday night after which noise levels are low to moderate for the rest of the week.
Category: GB2RS Propagation News
