[amsat-bb] Re: ALuminum Rod
Sil - ZL2CIA
zl2cia at paradise.net.nz
Wed Mar 21 19:55:01 PST 2007
GEORGE ABBOTT wrote:
> Hi: Can brass rods be used for antenna elements? Regards ,George Abbott
Yes and no. I have made antennas from brass rod and they worked just
fine, but would probably have worked a little better if they had been
made from aluminium (aluminum).
Brass rod is a nice material to work with. It's rigid and can be easily
soldered. However, the resistivity of brass is higher than aluminium and
the I squared R losses are higher. A little more of your Tx energy is
wasted warming your antenna if it is made from brass than would be if it
was made from aluminium. Most antenna manuals recommend against brass
because of this, although I'm not sure how "real" this loss is.
Intriguingly, one our our club members built himself a Q meter, and
demonstrated it at a club meeting by measuring the Q of loops of wire
from different materials. While brass did less well than than aluminium
or copper, galvanised iron wire was significantly better than brass.
This was surprising because zinc is generally considered to have a
resistivity only slightly less than brass. I built some antennas using
heavy galvanised fencing wire, based on the results of this test. They
were not a fantastic success.
If you already have the brass rod, then go ahead and experiment.
Radio data Reference Book: G. R. Jessop
ARRL Handbook 1992
Resistivity compared to copper (same as relative resistance)
Brass 3.7 to 4.9
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