[TowerTalk] 3-Stack Tribander Issues

W4PV w4pv at comcast.net
Thu Feb 25 04:20:02 PST 2010

Good Morning Wayne,

I used an old antenna program called Yagi Max.I recently acquired Eznec3.0 
but have not had a chance to learn how to use it.

My tower is 114 ft tall including mast, Rhon 45.  Using yagi max I tried 1 
wave, 0.5 wave and 0.75 wave length apart.  I then tried various spacing 
between ant. 1 and 2, and 2 and 3.  I settled on a distance of 1 wave 
between 1 and 2 (2.44 and 1.82 wave heights), with 5/8 wave between 2 and 3 
(1.82 and 1.19 wave heights) .  This gave me the fewest lobes off the back 
side and 14.32 dbi. forward gain.  According to yagi max this spacing 
developed a nice low angle main lobe and 2 minor lobes at about 45 degrees.

I am not an antenna specialist but I considered this to be the cleanest 
pattern both forward and reversed that I desired. Other spacings showed more 
minor loabes off the front and back patterns. The final spacing 113 ft, 84.1 
ft, and 55.2 ft. using the available space on my tower.  Scientific study, 
no, but it works for me.

Hope this makes some since.


Patrick, W4PV
Knoxville, TN 

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