Topband: Modeling verticals (fat, skinny, etc) on EZNEC

[Tom Rauch]

> horizontally polarized energy this would not happen. The 
> receive antennas mentioned
> cannot, using only one, distinquish between the combined 
> vertical/horizonal
> polarization of the tilted dipole and true circular 
> polarization.

It seems to be humans having the problem, not the antenna. 
:-)

If we placed a dipole high above ground and tilted it to the 
"north" 45 degrees at the top, it would simply generate an 
electric field  tilted 45 degrees to the "north" at the top. 
A single linear polarization. If we tried to receive that 
signal with an antenna tilted 45 degrees to the "south" at 
the top, we would have a polarization null. This would not 
be true with a circular polarized antenna.

Thus the picture in our minds that we have generated a 
vertical and horizontal polarization simultaneously at one 
point in space is very clearly **wrong**. It is wrong with 
an Inverted L, and the simultaneous multiple polarizations 
in one direction is also wrong with a leaky feedline Windom.

Now let's say we have a slowly rotating wave from a slowly 
changing ionospheric path. Statistically the tilted dipole 
is just as likely to have a response null as any other 
antenna we would have. Not so if we receive on a true 
circular polarized antenna, assuming a non-circularly 
polarized ionospheric signal.

A tilted dipole very clearly cannot be compared to circular 
polarization. In order to have multiple polarizations from 
one source we must rotate the wave with time. Otherwise we 
have a simple linear polarization that is tilted.

Anyway, EZNEC 4.0 allows us to see (in tabular form) just 
how much wave rotation we have and what direction it 
rotates. Without that rotation all we have is a single 
polarization.

73 Tom