[amsat-bb] Re: ALuminum Rod

[Sil - ZL2CIA <zl2cia@xxxxxxxxxxxxxxx>]

GEORGE ABBOTT wrote:
> Hi: Can brass rods be used for antenna elements? Regards ,George Abbott
> Ka1ajf

George,

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
Relative resistance
Copper 1
Aluminium 1.64
Zinc 3.4
Brass 3.9

ARRL Handbook 1992
Resistivity compared to copper (same as relative resistance)
Copper 1
Aluminum 1.6
Zinc 3.4
Brass 3.7 to 4.9

Sil
ZL2CIA




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