Re: [amsat-bb] Helical array

[Richard@xxxxxxxxxxxxxxxxx (Richard W L Limebear)]

Terry

>  I was wondering about ice build up in the winter on a helical antenna?
>  thats why I was thinking about the copper. 

Well .... I was in the West Indies; we don't get ice there (only in drinks).
I guess it depends on the physical strength of whatever you use. I omitted
to say that the broom-handle version was for 70cm; the 2m version used thick
wall plastic tubing. Some old heliax would make a really strong spiral.

The biggest limitation of helices is that they have fixed polarization. I
use switchable yagis nowadays.

> The array will be about 10
>  feet off the school roof so hopefully that will be enough clearance
>  from the stones over metal roof.

10ft is no problem; I had the spiral on the same mount as my HF beams and
the spiral (elevated 20 degrees) passed *through* the HF beam. Keep metal
away by at least one or two diameters of the spiral.

73
Richard W L Limebear G3RWL
g3rwl@amsat.org
FOC # 1188

          So many beautiful girls ..... (sob) so little time
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