[SADXA] Optimum GreyLine-Termination Angle for VK0EK (Heard) / AZ Propagation

[Jerry Wothe]

You have to consider what frequency you are working with also. The dark 
side is better for the low bands and the sunny side for the higher 
frequencies. Who is in the dark and who is in the light and when. If you 
are worrying about where to set your antenna, _+_ 10 degrees, very few 
antennas are that sharp that you can notice it. Plus depending on 
frequency the signal my not be best right on the great circle bearing. 
Lots of antenna rotating goes on right at SR/SS to find out just where 
is the signal coming from.

W6XI

On 4/3/2016 3:06 PM, W7EXG (Bill) wrote:
> By now, most of us have recognized the two opportunities per day, for
> propagation between AZ and VK0EK, due to the Greyline.
>
> QRZ bearing data shows 186 deg Short Path (SP) (6 deg Long Path (LP))
>
> The question becomes: Is this geometrical bearing, the correct bearing when
> Greyline propagation is being considered? I submit the correct answer is..
> Not Always.
>
> For April 4th, 0140Z UTC, the greyline passing through Tucson, also passes
> slightly West of Heard Island. The Greyline Terminator line is along the 7
> deg / 187 deg line. It is almost the perfect storm, since the Greyline
> propagation path is close to the required 186 deg SP bearing. As most of us
> know, the evening propagation for VK0EK has recently been exceptional.
>
> (HEARD considering staying put!)
>
> However, for April 4th, 1300Z UTC, the greyline passing thought Tucson,
> passes significantly more West of Heard Island. In this case, the Greyline
> Terminator line is along the 353 deg and 173 deg line.
>
> This suggests the morning propagation may be best at a SP bearing of 173
> degrees, not 186 degrees (a 13 deg bearing difference)
>
> Because of the further west Greyline for HEARD, and an indirect propagation
> path, this suggests the AM propagation between AZ and HEARD may currently
> not be as good as in the PM.
>
> This analysis is based on the greyline prediction websites.. some of which,
> may not yield identical results. The link below is easy to use, and will
> verify my analysis above. It agreed with several others greyline predictors
> I tried.
>
> https://academo.org/demos/day-night-terminator/
>
> 73s, and good luck with HEARD!
>
> Bill W7EXG
>
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