The short answer is that stainless probably won't make a noticeable
difference in loss, and therefore won't make a significant difference in Q.

The conductor loss of an antenna of a given wavelength size gets less as
the frequency gets higher. That's because the antenna length decreases
in inverse proportion to the frequency, while the loss per unit length
increases only as the square root of the frequency. So for a given wire
diameter, a half wavelength dipole at, say, 10 MHz has half the loss of
a half wavelength dipole at 2.5 MHz. Stainless steel whips are fine at 2
meters. But an 80 meter dipole made from small or moderate gauge
stainless wire could be pretty lossy -- almost certainly so, if the
stainless is a magnetic alloy. (Being magnetic greatly increases the RF
loss -- by a factor of the square root of the permeability.)

Loss becomes very important when a whip is a lot shorter than a quarter
wavelength. However, in many or most cases (like an HF mobile whip), the
whip typically has a fairly large diameter where the current is high,
and the whip loss is swamped by other losses, so the whip loss isn't
objectionable.

It's always possible to come up with a combination of whip diameter,
length, and frequency where stainless could be a poor choice -- but it's
uncommon in typical applications.

Roy Lewallen, W7EL

Paul Burridge wrote:
On Sun, 3 Aug 2003 11:40:55 -0400, "Bob Lewis \(AA4PB\)"
wrote:


Stainless steel is awful at conducting electricity - so it won't

make a

very efficient antenna.

I doubt that the difference in resistance between stainless and copper
is going to cause any significant additional losses in a whip antenna.
That difference will be small compared to the other losses. Stainless
is often used for whip antennas because of its mechanical properties.


Yes, I've several proprietory s/steel whip antennas that give
excellent results. But a question springs to mind. If a s/steel
antenna has slightly higher resistance, does that appreciably lower
its Q?


--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill