[TowerTalk] Two Vertical Antennas

[Roger D Johnson]

Roger Parsons wrote:
> I have separate 7MHz and 10.1MHz quarter wave vertical
> antennas which are spaced about 60' Both have about 60
> radials and the radial fields do therefore cross each
> other to some extent. There is a very small amount of
> interaction between them, as one would expect, but not
> enough to significantly affect the matching. The feed
> impedances are much as expected, so they both seem to
> be working as they should be. They are both fed over
> the same hardline feeder with a switch box near the
> antennas. I am sure there are no feedline, switchbox
> or matching faults - I have physically exchanged the
> feedlines. 
> 
> The 10.1MHz antenna works beautifully - I snagged YV0D
> the first call after I found his listening frequency
> last night in a major pileup. The 7MHz antenna is a
> dog, which is very easily beaten in all directions and
> distances by a dipole at 40'. (The dipole is about
> 300' from the verticals and has a higher loss
> feedline.)
> 
> Now why should that be?
> 
> 73 Roger
> VE3ZI
Hi Fellow Roger....

If I were to venture a guess I would say that was propagation.
Sometimes the low angles are favored (vertical) and sometimes
the high angles (dipole). I would try more comparisons over
longer paths through the Winter months. I suspect that you will
find some long path signals where the vertical handily beats
the dipole. Most DXers have both a high angle and a low angle
antenna for just these situations.

Good luck and DX, Roger

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