You may have noticed that for the past several months radio propagation has become extremely difficult, and it only seems to be getting worse as the days and weeks go by. No you are not immagining it, it is actually happening.
This is mainly because we are in the beginning of what is known as a "Solar Minimum". This basically means that the sun is at a very low point in its cycle with regards to energy that it sends out to the Earth and other planet in the galaxy.
Solar Minimums are nothing new. The Earth goes through them on a regular basis. Unfortunately there is no way of knowing at this point if this is your average, ordinary Solar Minimum or if this is what is known as a Grand Solar Minimum. Only time will tell the difference as a Grand Solar Minimum can only be confirmed after the event has comcluded and we are just at the beginning of this event.
The Solar Flux Index (SFI), also referred to as Radio Flux basically determines how "charged" the ionosphere is. The higher the number, the more charged the ionosphere, and thereby the better radio propagation is on the HF bands because more of the radio signal is able to be bounced off of the ionosphere back down to Earth.
This number can vary from as low as 50 to as high as 300. Low numbers indicate that the maximum useable frequency or MUF, will be low and over- all conditions will not be very good, particularly on the higher HF bands. Higher numbers indicate that there is sufficient ionozation in the atmosphere to support lomg-distance communications on the higher HF frequencies.
Below is a chart from NASA showing the predictions for SFI and the number of sunspots through the end of 2019.
The reason the predictions are showing the SFI and sunspots are continually dropping each month over the next year is because we are only at the start of the solar minimum. It is predicted to get worse for the next three years before we start to see any real improvement.
So, what does this mean for radio propagation? Generally speaking, as the SFI and sunspot numbers continue to drop we will also continue to see a decline in radio propagation, especially on the HF bands, as we have seen over the past few months.
Does this mean we will lose long-distance radio communications? I don't think that we will lose long-distance radio communications, but it will not be the same as it is now.
What I expect is that in order to maintain long-distance radio comms we will have to look at making adjustments to the type of communications we are using. What I mean by that is I expect voice radio communications to continue to deterio