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Old June 16th 04, 07:03 PM
Jimmie
 
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Default aNTENNA MATERIAL

I want to make a 2m Yagi out of stainless steel, partly because of the
corrosion resistance but mostly because I have the materials on hand. Some
of my friends have tried to tell me that the higher ohmic resistance of SS
will make for a poor antenna. Frankly I do see that it would make any
significant difference. While SS has several times the resistance of AL I
figure we are just comparing micro ohms to milliohms.at worst, probably more
like micro ohm to tens of micro ohms. I am a correct on these assumptions or
should I listen to my friends.


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Old June 16th 04, 08:57 PM
Ralph Mowery
 
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"Jimmie" Gfender@carolina dot.rr.dot com wrote in message
. com...
I want to make a 2m Yagi out of stainless steel, partly because of the
corrosion resistance but mostly because I have the materials on hand. Some
of my friends have tried to tell me that the higher ohmic resistance of SS
will make for a poor antenna. Frankly I do see that it would make any
significant difference. While SS has several times the resistance of AL I
figure we are just comparing micro ohms to milliohms.at worst, probably

more
like micro ohm to tens of micro ohms. I am a correct on these assumptions

or
should I listen to my friends.


If you have the materials go ahead and make the antenna. SS is just harder
to work with for most people and weighs more. YOu will loose some gain but
unless you are into very weak signal work it will not be too noticable. I
have an 8 element quagi for the 220 mhz band I made using SS welding rods
for the directors. It works beter than a 6 element beam I had up in the
same place. It also works much beter than the 11 element CC antenna that
was also in the same place.


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Old June 16th 04, 10:15 PM
 
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Use the SS. I just finished building a dual band J-Pole 2m/70cm and
used SS. It works just fine. 2m SWR ranges from 1.0:1 to 1.4:1 and I
have had great success hitting distant (40 miles) repeaters on ~5w at
only 20' AGL at my location, but about 5' BELOW average ground level
for the entire city... Go figure, I bought the place in the bottom of
the hole!





On Wed, 16 Jun 2004 18:03:58 GMT, "Jimmie" Gfender@carolina
dot.rr.dot com wrote:

I want to make a 2m Yagi out of stainless steel, partly because of the
corrosion resistance but mostly because I have the materials on hand. Some
of my friends have tried to tell me that the higher ohmic resistance of SS
will make for a poor antenna. Frankly I do see that it would make any
significant difference. While SS has several times the resistance of AL I
figure we are just comparing micro ohms to milliohms.at worst, probably more
like micro ohm to tens of micro ohms. I am a correct on these assumptions or
should I listen to my friends.


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Old June 17th 04, 12:38 AM
Hal Rosser
 
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go for it - the added R may increase bandwidth a little

"Jimmie" Gfender@carolina dot.rr.dot com wrote in message
. com...
I want to make a 2m Yagi out of stainless steel, partly because of the
corrosion resistance but mostly because I have the materials on hand. Some
of my friends have tried to tell me that the higher ohmic resistance of SS
will make for a poor antenna. Frankly I do see that it would make any
significant difference. While SS has several times the resistance of AL I
figure we are just comparing micro ohms to milliohms.at worst, probably

more
like micro ohm to tens of micro ohms. I am a correct on these assumptions

or
should I listen to my friends.




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Old June 17th 04, 06:18 AM
Wes
 
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On Wed, 16 Jun 2004 18:03:58 GMT, "Jimmie" Gfender@carolina
dot.rr.dot com wrote:

|I want to make a 2m Yagi out of stainless steel, partly because of the
|corrosion resistance but mostly because I have the materials on hand. Some
|of my friends have tried to tell me that the higher ohmic resistance of SS
|will make for a poor antenna. Frankly I do see that it would make any
|significant difference. While SS has several times the resistance of AL I
|figure we are just comparing micro ohms to milliohms.at worst, probably more
|like micro ohm to tens of micro ohms. I am a correct on these assumptions or
|should I listen to my friends.
|

Listen to your friends.



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Old June 17th 04, 06:19 AM
Wes
 
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On Wed, 16 Jun 2004 19:38:43 -0400, "Hal Rosser"
wrote:

|go for it - the added R may increase bandwidth a little

Yep, and while you're at it, add a 20 dB resistive pad at the
feedpoint. The bandwidth will be super.
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Old June 17th 04, 07:00 AM
Ian White, G3SEK
 
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Ralph Mowery wrote:

"Jimmie" Gfender@carolina dot.rr.dot com wrote in message
.com...
I want to make a 2m Yagi out of stainless steel, partly because of the
corrosion resistance but mostly because I have the materials on hand. Some
of my friends have tried to tell me that the higher ohmic resistance of SS
will make for a poor antenna. Frankly I do see that it would make any
significant difference. While SS has several times the resistance of AL I
figure we are just comparing micro ohms to milliohms.at worst, probably

more
like micro ohm to tens of micro ohms. I am a correct on these assumptions

or
should I listen to my friends.


If you have the materials go ahead and make the antenna. SS is just
harder to work with for most people and weighs more. YOu will loose
some gain but unless you are into very weak signal work it will not be
too noticable.


That's correct - especially the last part.

In typical yagi designs, resistive losses in normal aluminum elements
are on the order of a percent - which is negligible. There are many
grades of SS, of course, but again a typical value might be a few
percent.

In Europe there is a successful range of 'Flexa-Yagis' of very
lightweight construction using elements made from thin, springy SS wire.
These yagis are only about 0.5dB down in gain compared with ali elements
at 144MHz, and maybe 1dB at 432MHz.

A few years down the line, when ali elements may have corroded, the SS
elements may even come out ahead.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
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Old June 17th 04, 12:59 PM
Ralph Mowery
 
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Default


"Jimmie" Gfender@carolina dot.rr.dot com wrote in message
. com...
I want to make a 2m Yagi out of stainless steel, partly because of the
corrosion resistance but mostly because I have the materials on hand. Some
of my friends have tried to tell me that the higher ohmic resistance of SS
will make for a poor antenna. Frankly I do see that it would make any


Look at all the mobile antennas. For the most part they are SS. Mainly
because of the stiffness of the material. The antennas for the low bands
are usually not SS. Part of it is that the short for wavelength antennas
can not stand much resistance where it becomes a large part of the overall
"radiation resistance".
When the antenna is aproaching a 1/4 wave or more the resistance of the
material it is made of is less important.


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Old June 17th 04, 02:28 PM
Reg Edwards
 
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Default

The loss in a stainless steel whip antenna in comparison with the TOTAL
loss, including that in the ground, is always small enough to be neglected,
regardless of length of the antenna.


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Old June 17th 04, 02:31 PM
Cecil Moore
 
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Ralph Mowery wrote:
The antennas for the low bands are usually not SS.


In one of the CA 75m mobile shootouts, Wally, WA6JPR, entered
a bugcatcher with an SS Fortex Coil. It was 4 dB down from
his copper loading coil (no hat) and 6.5 dB down from the top
rated screwdriver (with hat). Of course, most stingers on HF
mobile antennas are SS and are located at the high voltage -
low current end of the mobile antenna.
--
73, Cecil http://www.qsl.net/w5dxp



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