Stainless steel elements.
 

Would there be a problem using stainless steel elements in a beam
antenna? Can I solder the lead in to stainless?

wrote in message
oups.com...
Would there be a problem using stainless steel elements in a beam
antenna? Can I solder the lead in to stainless?


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.
2) Stainless Steel is heavy. It means that the antenna would need to be
heavily constructed just to hold up it's own weight.
3) Stainless Steel can be soldered to but not easily. So can aluminum be
soldered but soldering is not the best way to make connections to antennas
even ones made out of copper as the solder doesn't hold up well in the
weather.
Of course there are some antennas that are made of stainless steel because
they need the corrosion resistance or the strength and flexibility of
stainless steel. Mobile whips come to mind for one case, the other would be
an antenna that is used in a corrosive environment like on a buoy at sea.
Of course if you need a antenna made out of a strong light weight corrosion
resistant metal, I know of one that's made from titanium. It's as strong as
steel, almost as light as aluminum and is a good conductor but it's very
costly compared to aluminum.


--
John Passaneau, W3JXP
State College, PA

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

How do I determine the length of elements for a stainless steel element
beam antenna?

What about the length of using stainless steel in a j pole?

In making a beam, if I wanted to use a metal boom, how could I insulate
the elements from the boom?
Please forgive me if these are elementary questions.

On 6 Jan 2005 06:14:21 -0800, wrote:
Please forgive me if these are elementary questions.

Hi OM,

We can forgive the questions, but they are far from elementary. In
fact, there are so many variables to consider, that it often makes
such questions hard to answer without going into a considerable length
of constraints.

One simple response, however, is that for VHF/UHF, stainless steel is
hardly the most complex issue - this has already been noted here in
discussion. The remaining characteristics of length, size, and
distribution of elements has as many answers as answerers³.

To put it bluntly, you should put some effort into coming to terms
with modeling software to appreciate the variety of answers and their
ramifications. Getting this same education through single one-off
questions could take many, many years.

Another way is to simply pick a design, and build it. When you
discover what's good or bad about it, THEN discussion could more
easily respond to what you have and what you need to do. Experience
is the great leveler against "what-if." One notable aspect of this
past time is you are NOT going to do this once! So you may as well do
something and expect you will do some more (and more...).

73's
Richard Clark, KB7QHC