Topband: EA to VE3 on 40m

[Carl K9LA]

Eddy VE3CUI commented:

>A non-related (but still interesting, from a low-band perspective) aside: listening at the bottom end of 40-meters at ~1100 UTC to-day, I copied a very 569 "EA1", and an equally strong "EA7" station calling CQ Contest...that would be at darn near high noon in Spain! 
>
>Looking at my "DX Edge" sliderule for October, I can't for the life of me see how their signals could make it across at that time. I called the EA1, but no luck...
>
Although 1100 UTC is around noon in Spain, the overhead Sun at the end 
of Septembder is just south of the equator - so the solar zenith angle 
on the EA-to-VE3 path never gets below about 53 degrees. With 
ionospheric absorption inversely proportional to the solar zenith angle 
and also inversely proportional to the square of the frequency, 40m at 
this time of year (and in the forthcoming winter months) on higher 
latitude paths can withstand quite a bit of "daylight". VOACAP, with 
400W and dipoles, predicts a monthly median signal of -104dBm on this 
path at 1100 UTC, which is around S3. So S6 isn't out of the question on 
"good" days.

Carl K9LA