"Art Unwin" wrote in message
...

The parabala [sic] is based on inter
inductive coupling
of a dipole so the parabola reflects at maximum current amplitude.

Plane wave reflection from a parabola doesn't have a discrete current
maximum, per se. You are not describing an antenna element whose current is
maximum at the feed point, etc, etc.

The helix reflector is not based on
coupling but the true mechanical impact of particles which is vastly
different.

Maybe true, maybe not. Irrelevant either way. No 160m helix antennas.

... it is always best to initial perform the calculation
from first principles to ensure that the formula is applicable
where you intend to use it.

I did that, it was, and I'm grateful to have your support.

"Sal"