Propagation News – 16 September 2018

| September 14, 2018

Last week started with stable solar conditions, but very low activity.

After 14 days without sunspots, two small, new spots turned up. Sunspot number 2721 existed for Sunday and Monday, then disappeared by Tuesday. Sunspot number 2722 popped up on Wednesday and Thursday, and was gone by Friday. Neither of these spots has disappeared altogether. They can hide below the visible disc of the Sun and may reappear before they rotate to the far side.

Warnings of increased geomagnetic activity were announced by the Space Weather Centre and indeed the A-index and the K-index rose significantly, to 35 and 6 respectively. These index figures were the result of a major geomagnetic storm that peaked at 2135UTC on Tuesday evening.

Solar wind picked up and reached a maximum of 624 kilometres per second at 0438UTC on Wednesday. The magnetic field carried by the solar wind disrupted that of the Earth and disturbed propagation conditions.

Maximum useable frequencies for long-skip distances generally varied between 15 and 18MHz, with a short burst when it reached 21MHz at 1900UTC on Monday.

Workable DX paths were open, as confirmed by reception of some of the International Beacon Project transmitters on 14.1MHz. Found on the frequency were beacons in the Far East, South Africa, Venezuela and USA. The strongest of the beacons, but admittedly not big DX, was CS3B in Madeira, whose carrier level was still audible down at the QRP 100 milliwatt level.

An interesting propagation event to look forward to next weekend is the equinox on the 22 September. This is the time, plus or minus a few days, for operators to take advantage of greyline propagation on the low HF bands of 1.8 and 3.5 MHz between the ultimate DX path—United Kingdom to New Zealand. There isn’t time here to explain greyline working, but many propagation books cover this interesting topic. Good luck with the DXing.

VHF and up

The weather patterns this coming week look distinctly autumnal with some unsettled weather on the charts and some quite strong winds at times. There are some fleeting periods of high pressure in the south with the attendant chance of tropo giving some lift conditions, especially in the foggy early mornings.

The windier spells may test your antenna guy ropes, with one model suggesting a small low crossing the country just before mid-week. Obviously it’s too far ahead to be certain which model has called this correctly, but it shouldn’t be a surprise that it’s turning unsettled as we move towards the second half of the month.

With the moon at maximum negative declination early this week, and apogee on Wednesday, the Moon will only get low on the Horizon for a few hours a day and EME path losses will be at their highest.

With the windy conditions predicted, and no major meteor showers it’s probably a week for catching up with some indoor system improvements.

There’s always the artificial satellites to keep VHFers interested so update the prediction software and have a go.

Category: GB2RS Propagation News