RadioBanter - View Single Post - Stacking Satellite VHF and UHF F9FT Antennas

December 3rd 05, 10:10 AM posted to rec.radio.amateur.antenna

Tom Ring ha scritto:

wrote:

Hello all,

I actually own a 2x9 VHF and a 2x19 UHF by F9FT (Tonna).
Since I need better performance (especially on VHF) for LEO operations
I was thinking about stacking another antenna identical to the one I
already have.
The suggested stacking distance is 2.77 m. Since I am doing this
upgrade I tought about stacking another UHF antenna too so that I would
have an horizontal mast 3 meters long, with the VHF yagis at the ends
and the UHF yagis in the middle.

I have some questions:
1) Will the UHF yagis create troubles to the VHF since they are in the
middle?

No.

2) What kind of real performance increase will I experience on VHF?

If the spacing is correct you will see roughly 3dB.

3) Can I couple the vertical elements with a coupler and the horizontal
elements with another coupler and then apply a RCHP/LCHP coupling
harness like I would normally do on a single antenna?

This doesn't match what you are speaking of in questions 1 and 2. You
cannot have the gain you desire and have the second set of antennas
differently polarized. That is a different configuration which requires
a feed that gives you circular polarization.

Maybe I did not explain my question well. Considering only the VHF
antennas, I want to couple separately the vertical dipoles and the
horizontal ones. Then I could have two separate antenna feeds, one for
the vertical and the other for the horizontal plane. More pratically I
could use a coaxial relay to be able to switch between vertical and
horizontal.
The question is: can a system like that still be somehow used to have
RHCP and LHCP? Do I simply have to couple the two feeds like I normally
do with single antenna?

Thanks

Alain
iz6byy ww3ww