Topband: Are stacked verticals feasible?

[Mike Armstrong]

Tom and all,
If I am reading the question correctly, aren't we talking about something that is done at VHF/UHF with great regularity?  Stacked vertical elements, stacked vertically polarized beams and all manner of stacked vertical "anything" are done there all of the time to avoid cross polarization loss when the other stations (especially mobile) are the main users.  

So understanding that it is done at those frequencies, the answer to the original question of "can it be done," so to speak, is a resounding YES.  I just don't have any idea how you could extrapolate that to MF (160 meters)...... It would be a monstrously tall structure..... he he he.  Actually, I have a set of stacked vertical beams that I use for a point-to-point link with a marginal repeater from my cabin up in the high country on the Mogollon Rim in AZ...... It is an incredibly effective antenna that was much less so with a single vertical beam..... Hopefully I didn't just waste everyone's time by misinterpreting the question..... :) :)

Mike AB7ZU

Kuhi no ka lima, hele no ka maka

On Sep 6, 2013, at 2:46, "Tom W8JI" <w8ji at w8ji.com> wrote:

>> Isn't this a "Vertical dipole"? Two quarter wave radiating elements? And tower behind it will be some kind of reflector/director depending on height. The radials seem unimportant if thought of this way.
> 
> Antennas radiate because of the current flow.
> 
> So you would have two current maximums, one maximum near the earth for the lower element, and another maximum  higher up about 1/4 wave away from earth.
> 
> The end result would be earth conductivity dependent, but somewhere between a little better or a little worse than a 1/2 wave vertical. The spacing of current maximums would be a little wider than a vertical dipole or half wave vertical, but still too close for any real significant gain. Because a current maximum would be at earth level, ground losses might eat up any very small gain.
> 
> Maximum stacking gain with 1/4 wave between current maximums is about 0.5 dB. This is reduced because the bottom element is against earth, and could even go negative. Most of any gain, if it had gain, would come from the top element and the earth reflection. 
> _________________
> Topband Reflector