On Thu, 14 Sep 2006 20:41:53 GMT, Paul Monaghan
wrote:

Reading the archives I can't tell whether to go with the copper
because it is a better conductor than the others, with the aluminum
because it is thicker than the copper, or with the galv pipe because
it is much thicker than the copper though somewhat lossy.

It's a mechanical decision, mostly. The antenna has to be 1/2
wavelength long (and vertical) for best reception, so consider that
when you decide what to use.

My personal decision would be a ground plane, not a dipole. Radials
(the horizontal elements) about 75" each (for the 39 MHz signals) and
a few vertical elements - one 75" long, one about 26" long for the
aircraft band and another about 19" long for the 150-160 MHz range.
(You can add as many as you like - the only constraint is mechanical -
how do you do it?)