TopBand: RE: Poor 160 Conditions

[Robert Brown]

Friends in Radio Land,

There is more than enough ionization overhead to support 160 meter
propagation.  Put another way, MUFs are not an issue.  Period.  But
magnetic activity with higher SSNs continues to be a problem, even at
mid-latitudes.

There will be two other effects due to rising solar activity:

1) a slight rise in ionospheric absorption during quiet days, just as
there is a slow rise in foE with increasing SSN.  You will see this in
Figure 5.13 in Davies' new book.

2) there will be a slight increase in the radiation angle needed to get RF
past the peak of the E-region at night.  That is the case as the effective
vertical frequency must increase to go along with the slight change in
foE at night.  The rise in foE means that more RF goes on E-hops, with
accordingly greater signal losses for a given power output.

By all accounts, there must be other variables at work but there seems to
be a lack of data to use in making comparisons.  The matter of Stratwarms
has been laid to rest by K9LA's nice work.  There may be a role for
atmospheric density changes but we will not know about that until there
have been more magnetic storms and, hopefully, VK3QI will be able to see
if they produce travelling ionospheric disturbances or not.  VE7DXR is
looking at dawn enhancements but has not collected enough records to make
any kind of data analysis.  Beyond those ideas, let me say that recently,
I called attention to the role of atmospheric ozone but at the moment,
that only seems to be related to the variability of DX conditions close to
sunrise.  I continue collecting data and may have more results later in
the year.
 
So features of 160 meter DXing still elude us but there seems to be no
loss in interest.  That's all to the good.

Have a Happy Holiday Season,

73,

Bob, NM7M



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