news wrote:

Hi:
There are some problems with using stainless steel for elements in a beam.
1) Stainless Steel has much higher loss than aluminum. Remember because of
skin effect the RF current flows only in the outer few thousand of an inch
of the metal. The depth of conduction gets less as the frequency goes higher
so 2m antenna made of stainless would have higher loss than a 6m and 440
antenna would have even more. . . .

If you do the actual calculations, you'll find that even the greater
loss of stainless is insignificant for typical VHF and higher frequency
antennas, even when made with wire of moderate diameter. When made with
tubing, loss is even less.

And, it's not necessarily true that antenna loss increases with
frequency. The skin depth decreases only as the square root of
frequency, while for a given antenna length in wavelengths, the element
length is inversely proportional to frequency. For example, if you
increase the frequency by a factor of two, the skin depth decreases by a
factor of about 1.4 while the length shortens by a factor of 2. The net
result is *lower* total resistance as the frequency increases -- a
factor of about 0.71 each time you double the frequency. (This is
assuming that you maintain the same absolute conductor diameter and keep
the length constant in terms of wavelength.) That's why stainless steel
isn't a problem for higher frequency antennas.

Roy Lewallen, W7EL