Topband: Inverted V antenna!

[Tom Rauch]

> The results show that it is a BETTER VERTICAL  than horizontal by 3dbi
> at a elevation angle of 20 degrees to the horizon.  This is off the
> ends. Horizontal is broadside.

Hi Don and all,

I may not have expressed it as well as possible, but this is worth 
going over if you really want to know what polarization an antenna 
has.

All horizontal dipole style antennas gradually tilt the radiation 
towards vertical off the ends. As a matter of fact, radiation off the 
ends is almost exclusively vertical. That's true for perfectly 
horizontal dipoles as well as Inverted Vee dipoles.

This is so contrary to logic most of us would place a dipole's ends 
towards a vertical to null the vertical, when the very opposite is 
true! If I want to null a vertical's radiation from a dipole at the 
same location the deepest null in coupling occurs when the dipole is 
broadside to the vertical! Maximum coupling occurs off the ends of 
the dipole. 

Which begs the question, how many people with dipoles, especially 
those near other structures, really have horizontal polarization in 
the directions they think? Probably very few of us do.

The actual radiation at any given point in this example is always a 
single polarization, but Eznec and other simple programs can not 
display "tilt" in the electric field. The simple display in the 
programs only expresses the field at two reference angles, vertical 
and horizontal.

When we see equal vertical and horizontal components it actually 
represents a wave that is tilted 45-degrees, the wave is neither 
vertical or horizontal. Unfortunately without phase we can't tell if 
the wave polarization, when viewed looking towards the antenna, is in 
a line between lower left and upper right or upper left to lower 
right. Rest assured whatever tilt angle the electric field has in any 
given direction and angle, rotating 90 degrees from it is a perfect 
null, so it is a single polarization and not a mix. (Which was my 
point.)

Now imagine the great difficulty in predicting how antennas interact 
with other things based on what we intuitively "feel", or what we see 
when we look at the antenna, or at the pattern when expressed as a 
ratio between two fixed reference of purely vertical and purely 
horizontal electric field alignment.73, Tom W8JI
W8JI@contesting.com