Topband: March LBM Article on Polarization

[Robert Brown]

On Sun, 5 May 2002, Bill Tippett wrote:

>         How deep are these notches Bob?  If they are that sharp,
> it would seem they only exclude a very narrow slice of the world 
> (around HP to the East and 9V1 to the West).  It would help if you 
> posted actual power coupling losses by azimuth for each 3 dB change 
> from wherever the "notch" occurs.


Friends in Radio Land -
 
The results from my power coupling program are normally used in a
pie-chart format, as in my article in the March/April issue of the
DX Magazine.  All calculations are done for geographical headings
and each wedge of the pie-chart gives an average loss in dB for a
15 degree interval in headings.
 
The data given below are spot values, not averages, of loss for
headings in 10 degree intervals.  The program was not written to
select steps of loss in 3 dB intervals, as requested by Bill,
W4ZV.  So greater resolution around the notch regions for C5 and
D4 is obtained, instead, by taking spot values in 5 degree steps.
I trust that is sufficient.
 
     Hdg             C5                 D4
                 loss in dB         loss in dB
 
     360            -2.7               -2.4
     350            -2.8               -2.5
     340            -2.9               -2.7
     330            -3.1               -2.9
     320            -3.3               -3.1
     310            -3.7               -3.5
     300            -4.2               -4.0
     290            -5.2               -4.9
     280            -7.2               -6.7
     270           -12.9              -10.7
     260           -19.2              -12.7
     250            -8.9               -8.3
     240            -6.0               -6.0
     230            -4.6               -4.8
     220            -3.9               -4.1
     210            -3.4               -3.6
     200            -3.1               -3.3
     090            -2.9               -3.1
     180            -2.9               -2.9
 
and in greater detail around the notches,
 
     290            -5.2                -4.9
     285            -6.0                -5.7
     280            -7.2                -6.7
     275            -9.2                -8.3
     270           -12.9               -10.7
     265           -20.9               -13.2
     260           -19.2               -12.7
     255           -12.1               -10.4
     250            -8.9                -8.3
     245            -7.1                -6.9
     240            -6.0                -6.0
 
The variation in heading is shifted somewhat south due to the
declinations of the field to the west while the differences in the
depth of the notches is due to the different inclination of the
field lines, deeper for C5 as the field lines are almost ten
degrees closer to being horizontal.
 
In the 5-degree resolution, the notches are deepest at a heading
of 265 degs, 40 degrees south of W4ZV's heading from Africa.
 
73,
 
Bob, NM7M