Centuries past there was a cold spell on Earth where it is stated
radiation propagation did not occur because of the lack of sun spot
observations. This period lasted about 30 years if my memory is
correct.
Now we appear to be in a state of global warming presumably because of
the actions of the Suns vibrancy which would suggest the present
increase in sunspot activity of the past century will continue to
increase and the next Sun spot cycle will be a good one. So don't give
up on antenna experiments just yet as the particulates will be a
coming
Art KB9MZ...xg