IT9GSF wrote: Do I have to consider interaction between the antennas in
the two options?
Yes, definitely. A quick look with EZNEC was surprising. Two of these
at right angles to each other with one of the vertical elements from
each antenna very close together produced very little interaction.
However as soon as I included the towers into the model the radiation
pattern was pretty much destroyed, to the point that a dipole at 50 ft
had more gain than the half squares at all elevation angles. A 90 to
100 ft tower is close to being resonant on 80 meters. Even when the
towers were made far from resonant, there was still a significant effect
on the pattern. I didn't include the guy wires into my model, but I
would suspect that they would also have a significant effect.
Before going to all the trouble of building this, I would recommend an
analysis with a full blown model including all towers, guy wires, any
antennas on the towers, and whatever other wires might be close. You
can use that model for testing the effects of detuning the towers and
guy wires and changing the spacing between the wires and the towers, and
make a decision if the final results are worth the effort of building it.
I didn't notice a quick fix to this problem.
Jerry, K4SAV
Fabio Grisafi wrote:
> I wish to build a double HALF SQUARE for 80 meters.
>
>
> Two options:
>
>
> 1) Three towers in a triangle with a relay switch atop a tower (South
> tower) that switches between the horizontal wires that continue with
> vertical wires in the two towers (one at NE and one at NW).
>
> 2) Four towers with different coaxial cables switched at the station.
> First antenna beamed NW-SW with two towers at NE and SE. Second antenna
> beaming East-NorthEast/West-SouthWest.
>
>
> Do I have to consider interaction between the antennas in the two options?
>
>
> 73 de Fabio, IT9GSF.
>
>
>
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