[TowerTalk] Stacking V-UHF antennas.

[Jim Lux]

At 06:19 PM 10/10/2006, Jim Lux wrote:
>At 04:30 PM 10/10/2006, Julio Peralta wrote:
> >Am I correct in my thinking that when you stack 2 antennas the E-plane
> >beamwidth is halved.
>
>Assuming you've got vertically polarized antennas, (i.e. you're
>stacking in the E-plane), the beamwidth will be reduced, but not
>necessarily by half.
>
>As a first approximation, your pattern would be the individual
>antenna pattern multiplied by the pattern of two isotropic antennas
>separated by the stacking distance.  If you stacked the antennas,
>say, 20 wavelengths apart, you'd have very narrow "interferometer"
>lobes a few degrees wide and a few degrees apart, with the outer
>lobes reduced by the antenna pattern.
>
>As an example, two isotropes one wavelength apart have a beamwidth of
>about 29 degrees.

here's a web page with a link to an excel spreadsheet that will let 
you play with it for yourself:

http://home.earthlink.net/~w6rmk/antenna/stacking.htm



> >In my case I'm going to stack 2 VHF beams for 2M
> >that have a 35 degree E-plan beamwidth I think it will be 17.5 degrees
> >after stacking them one above the other.
>
> >  I also think the H-plane
> >beamwidth will not change.
> >
> >Am I right or wrong?
> >
> >Julio, W4HY
> >
> >
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