Dave WX7G wrote:
For DX we are interested in elevation angles from 3-15 degrees. How much
error is there in a NEC model of a monopole at these elevations?
The link below shows the NEC4.2 fields for a seawater path on 1850 kHz. The
calculated field at 1 km in the horizontal plane for 1 kW of applied power
is 309 mV/m.
The theoretical maximum field for that system at 1 km in the horizontal
plane, over a perfect ground plane is 313 mV/m.
The fields at low elevation angles above the horizontal plane are nearly the
same. As NEC calculates the horizontal plane field accurately, the other
fields shown there will be equally accurate.
As shown in my earlier plot for seawater, 5 mS/m and 1 mS/m, the shapes of
the elevation patterns close to a monopole are very similar to each other
for those different conductivities.
http://i62.photobucket.com/albums/h85/rfry-100/160m_Qtr_Wave_ElPat_at_1km.jpg
R. Fry
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Topband reflector - topband@contesting.com
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