Re: [HCDX] Re: Antipodal Focusing

[Walter Salmaniw <salmaniw@xxxxxxx>]

At 05:49 PM 9/5/2003 -0400, Thomas Giella KN4LF wrote:
> I said at or NEAR the antipode. For instance the antipode from Plant City,
> FL, USA is well off of the west coast of Australia in the Indian Ocean but I
> regularly work into central and western Australia, on 160 meters phone with
> 100 watts because it's NEAR the antipode.

Thomas, have a look at this antipodal projection.  Now perhaps western 
Australia on 160 m would propagate well, but from experience, dawn 
enhancement to that part of the world (Grayline propagation) does wonders 
from the west coast on medium wave to the tropical bands.  (I speak from 
many sessions out at Grayland, WA and Sombrio Beach, BC).  Take a look 
where Thailand is, though.  This is no where near the antipode, and I would 
state again that this simply is not antipodal propagation.  Again, Thailand 
provides excellent grayline opportunities at certain times of the year 
(we've heard VOA from Thailand on MW at very strong levels at Grayland, WA 
using Beverages.  If it was antipodal propagation, all of the Beverages 
would be expected to perform equally well (ours are West, South-West, and 
North-West oriented), as at the time of monitoring, there is a darkness 
path in the directions of all of the Beverages.  This is not the 
case.  Typically, one Beverage always outperforms the others, and it's not 
always the one you might expect (probably due to ionospheric 
ducting/refraction).

http://jidanni.org/geo/antipodes/images/world.png

Another projection which I have found very useful and interesting is found 
here:

http://www.wendycarlos.com/maps/nadirs.jpg

Notice Hawaii is smack dab in Zambia, while New Zealand extends across 
Portugal and Spain. It looks like the antipode of Thailand is in fact off 
the west coast of South America.  I've printed this map off and use it in 
my DX binder.  Most of North America is not very useful when it comes to 
the antipode, lying in the Indian Ocean towards Antarctica.

.............Walt Salmaniw, Victoria, Canada.


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