Archive for June, 2016

Making Waves – HF Conditions….

June 19, 2016 1 comment

I read with interest a letter in the latest issue of Radcom entitled “HF Conditions – If only!”.  In it the writer laments over the lack of DX opportunities available on a daily basis as compared to how it was when he was an SWL 40  – 50 years ago.  I could also speak of similar things.  When I got my 1st licence in the late ’90s (VHF only B licence), we were at the peak of Solar Cycle 23 and  144MHz was like 20m is nowadays and there was always DX to work.  When I took the 12wpm CW test and got my current HF licence in 2000 we were still being blessed with excellent HF conditions and I managed to work amazing DX suing just a base loaded magnetic mount antenna for 15m sat on top of the ATU inside the shack – at night too!  The peak of solar cycle 24 was nothing to write home about though and the peak has now passed.


Solar Cycle 23


Solar Cycle 24

The above two graphs represent Solar Cycle 23 and Solar Cycle 24 for comparison.  It can be seen that at the peak of cycle 23 (2000) we had a daily sunspot count of approximately 120 whereas at the peak of cycle 24 (2014) the daily sunspot count was closer to 80.  The lower number of sunspots results in more coronal holes in the sun which lead to masses of plasma being ejected towards the earth, resulting in more geomagnetic storms (aurora).  This in turn gives rise to some enhancements in VHF (50MHz, 70MHz) but poor conditions on HF.


Solar Cycle 22

Looking back further to Cycle 22, it can be seen that the peak was even higher with a daily sunspot count above 150.  If this trend continues could it be possible that we are heading for another Maunder’s Minimum where there will be no peak for the complete cycle?  Will this mean a total flattening of the HF conditions?  It certainly would spell bad times ahead for the higher HF bands above 18MHz.  Fingers crossed it won’t come to that and our local star will become a little more active at it’s next cycle peak in 2020/21.