[TowerTalk] 2 Element Parasitic Vertical for 160M

[Jim Brown]

On Mon, 23 Nov 2009 15:01:13 -0600, Stan Stockton wrote:

>Am I missing something in the way I am modeling it or should I 
expect to see the results shown by the computer.  I am suspicious of 
the model since I can change the vertical portion of the reflector 
to #10 wire instead of #18 wire and the max gain moves up about 40 
khz.  I would have thought it would have moved it down some?

Stan,

I have a lot to learn about Yagis (and this is sort of a Yagi, if I 
understand what you're doing), but I've been studying a bit in the 
ARRL Antenna Book and building some Yagis. One thing I think I've 
learned is that the thing that makes it work is the phase of the 
current in the passive elements, which is set by their physical 
length as a fraction of a wavelength. As I understand it, the 
resonance of the driven element does not matter (or does not matter 
much) in determining directivity, and can be varied to achieve a 
match (with the hairpin or gamma or whatever).

Others may know a lot more than I do about this, so take this as a 
clue, not a definite "I know this for sure" sort of reply.

73,

Jim K9YC