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

[Tom Rauch]

> No, both EZNEC and elementary physics show that an E-W 
> dipole
> sloped 45 degrees radiates exactly equal amounts of both
> vertical and horizontal polarization in N and S directions
> with zero elevation, in free space.

The reason you see that display is the program only tells 
you level in two planes, perfectly vertical and perfectly 
horizontal. The reason you visualize it is you are 
visualizing wrong.
The fact the display shows only two planes and must display 
a tilted field as a combination of the two when it really 
isn't leads people to erroneously believe they have the best 
of both worlds, an antenna that radiates both vertical and 
horizontal. In fact true at all.

The field actually is a single polarization that is neither 
vertical or horizontal, but some angle between. Exactly 90 
degrees from that polarization alignment is a null, so we 
have a single tilted polarization NOT a combination of both. 
For example as we are broadside to a perfect dipole the 
field is perfectly horizontal. As we move off towards the 
ends the field tilts, with maximum tilt towards vertical 
near the ends. But at EVERY point it is a single 
polarization that simply is tilted.

The only way we can have both polarizations present in a 
single direction is by having a field that rotates with 
time.

Eznec+ 4 allows you to go into a menu that gives field 
strength in tabular form. From that menu you can see exactly 
how much rotation the field has. You will see a bent dipole, 
unless very specific conditions are met with length and 
angles, simply generates a single polarization that has 
various tilts in various directions. It dispels the myth 
that we can "mix" two polarizations without a quadrature or 
near quadrature phase relationship (so the wave rotates) and 
have both polarizations. Unless we change the polarization 
with time, it can only be a single polarization in a single 
direction.

73 Tom