Aurora
Aurora can also cause DX. Southern
DX'ers may never experience it, but it becomes more and more frequent at more
northerly latitudes. Bureau of Standards Radio Station WWV advises of magnetic
disturbances and auroral activity periodically; you can also spot auroral
conditions from blackouts in reception from northerly stations on mediumwave
and shortwave.
Of all ionospheric propagations, aurora
is probably the one most observed on the high VHF band (but not UHF) as well
as the low. But it's quite difficult to identify television video via aurora,
because of very heavy distortion and interference (as you can imagine from
viewing an aurora, it's hardly a perfect reflector). You may have a chance on
the audio side, however. FM and VHF radio DX'ers are much more successful at
auroral DX'ing, with distances typically in the 400-800 mile range, but with
no specific lower or upper limit. You may find that the signal is not coming
from the direction you would expect. It is bouncing off the auroral curtain,
which may be as much as 45 or 90 degrees away from the direction of the
station, but not necessarily at due north. Auroral activity is most likely
around the equinoxes, but may happen at any time when the proper solar
disturbances occur. Heavy auroral activity can also induce regular Es during
the following day or two and at 27-day intervals coinciding with the rotation
of the sun.
|
