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

On Sun, 03 Aug 2003 22:51:50 -0700, Roy Lewallen
wrote:

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.


[thorough-sounding explanation snipped]

Thanks, Roy. Sounds like i should be okay with ss at 40Mhz for this
purpose, then. I've been up to see my supplier in N. London today and
returned with a good selection of various ss spring wire to try out.
I'm given to understand that the rx antenna length isn't that
important with this r/c stuff, so I guess 30-35 inches should be fine.
I'll mount it in a conical well with curved sides as someone else
suggested to minimise any stressing.
--

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

In article ,
Paul Burridge wrote:

Thanks, Roy. Sounds like i should be okay with ss at 40Mhz for
this purpose, then. I've been up to see my supplier in N. London
today and returned with a good selection of various ss spring
wire to try out. I'm given to understand that the rx antenna
length isn't that important with this r/c stuff, so I guess 30-35
inches should be fine. I'll mount it in a conical well with
curved sides as someone else suggested to minimise any stressing.

Paul, it sounds like you need to get yourself a CPC catalogue,
pdq. It is similar to RS/Farnell, but the product range is more
aligned to your specific needs.

eg, In the Aerial section there are standard flexible and
super-flexible whip aerials, for cars. Wideband AM-FM reception,
complete with adjustable mounting block and output cable+plug.
About 340mm long on avg. Prices range from £2:92, to a horrific
£4:86.

Note also that CPC does a range of build-it-yourself kits. eg,
Part number HK00224 is a wideband antenna amplifier kit. Metal
cased (24x36x86mm), with 22dB of gain over the range 10-150MHz.
Price is a bank-breaking £7:49.

See http://www.cpc.co.uk or 08701 202530 for a printed
catalogue or CDROM. Farnell own CPC, so if you have a
Farnell account you also automatically have a CPC account.

--
Tony Williams.

On Tue, 05 Aug 2003 08:03:45 +0100, Tony Williams
wrote:

Paul, it sounds like you need to get yourself a CPC catalogue,
pdq. It is similar to RS/Farnell, but the product range is more
aligned to your specific needs.

Curious. I've never heard of 'em!

eg, In the Aerial section there are standard flexible and
super-flexible whip aerials, for cars. Wideband AM-FM reception,
complete with adjustable mounting block and output cable+plug.
About 340mm long on avg. Prices range from £2:92, to a horrific
£4:86.

Note also that CPC does a range of build-it-yourself kits. eg,
Part number HK00224 is a wideband antenna amplifier kit. Metal
cased (24x36x86mm), with 22dB of gain over the range 10-150MHz.
Price is a bank-breaking £7:49.

See http://www.cpc.co.uk or 08701 202530 for a printed
catalogue or CDROM. Farnell own CPC, so if you have a
Farnell account you also automatically have a CPC account.

Well I do already have a Farnell a/c so I'll give em a try! Thanks for
the suggestion.

--

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

On Tue, 05 Aug 2003 08:03:45 +0100, Tony Williams
wrote:

Paul, it sounds like you need to get yourself a CPC catalogue,
pdq. It is similar to RS/Farnell, but the product range is more
aligned to your specific needs.

Curious. I've never heard of 'em!

eg, In the Aerial section there are standard flexible and
super-flexible whip aerials, for cars. Wideband AM-FM reception,
complete with adjustable mounting block and output cable+plug.
About 340mm long on avg. Prices range from £2:92, to a horrific
£4:86.

Note also that CPC does a range of build-it-yourself kits. eg,
Part number HK00224 is a wideband antenna amplifier kit. Metal
cased (24x36x86mm), with 22dB of gain over the range 10-150MHz.
Price is a bank-breaking £7:49.

See http://www.cpc.co.uk or 08701 202530 for a printed
catalogue or CDROM. Farnell own CPC, so if you have a
Farnell account you also automatically have a CPC account.

Well I do already have a Farnell a/c so I'll give em a try! Thanks for
the suggestion.

--

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

In article ,
Paul Burridge wrote:

Thanks, Roy. Sounds like i should be okay with ss at 40Mhz for
this purpose, then. I've been up to see my supplier in N. London
today and returned with a good selection of various ss spring
wire to try out. I'm given to understand that the rx antenna
length isn't that important with this r/c stuff, so I guess 30-35
inches should be fine. I'll mount it in a conical well with
curved sides as someone else suggested to minimise any stressing.

Paul, it sounds like you need to get yourself a CPC catalogue,
pdq. It is similar to RS/Farnell, but the product range is more
aligned to your specific needs.

eg, In the Aerial section there are standard flexible and
super-flexible whip aerials, for cars. Wideband AM-FM reception,
complete with adjustable mounting block and output cable+plug.
About 340mm long on avg. Prices range from £2:92, to a horrific
£4:86.

Note also that CPC does a range of build-it-yourself kits. eg,
Part number HK00224 is a wideband antenna amplifier kit. Metal
cased (24x36x86mm), with 22dB of gain over the range 10-150MHz.
Price is a bank-breaking £7:49.

See http://www.cpc.co.uk or 08701 202530 for a printed
catalogue or CDROM. Farnell own CPC, so if you have a
Farnell account you also automatically have a CPC account.

--
Tony Williams.

On Sun, 03 Aug 2003 22:51:50 -0700, Roy Lewallen
wrote:

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.


[thorough-sounding explanation snipped]

Thanks, Roy. Sounds like i should be okay with ss at 40Mhz for this
purpose, then. I've been up to see my supplier in N. London today and
returned with a good selection of various ss spring wire to try out.
I'm given to understand that the rx antenna length isn't that
important with this r/c stuff, so I guess 30-35 inches should be fine.
I'll mount it in a conical well with curved sides as someone else
suggested to minimise any stressing.
--

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