Hello All,
I am building a DL6WU Yagi for 2 metres and am wondering if 1/4 inch
stainless steel tube would be okay for the directors and reflector. I
have been given some so it would save me from having to buy aluminium.
I will still use aluminium for the folded dipole and for the boom. Any
thoughts would be welcome.
Cheers
Max

wrote:
Hello All,
I am building a DL6WU Yagi for 2 metres and am wondering if 1/4 inch
stainless steel tube would be okay for the directors and reflector. I
have been given some so it would save me from having to buy aluminium.
I will still use aluminium for the folded dipole and for the boom. Any
thoughts would be welcome.
Cheers
Max


It will probably be a bit lossier than using Al but my first Yagi on 288
MHz(in the early 60s)was made out of 8g fencing wire and it seemed to work
reasonably well. Try the evaluation version of Eznec - I think you can
specify the material.
Alan

wrote:
Hello All,
I am building a DL6WU Yagi for 2 metres and am wondering if 1/4 inch
stainless steel tube would be okay for the directors and reflector. I
have been given some so it would save me from having to buy aluminium.
I will still use aluminium for the folded dipole and for the boom. Any
thoughts would be welcome.
Cheers
Max

Just checked - tried a 6m yagi and with Cu elements, gain is 9.64dB With
SS elements, gain is 9.41 dB
Alan

In message , Alan Peake
writes


wrote:
Hello All,
I am building a DL6WU Yagi for 2 metres and am wondering if 1/4 inch
stainless steel tube would be okay for the directors and reflector. I
have been given some so it would save me from having to buy aluminium.
I will still use aluminium for the folded dipole and for the boom. Any
thoughts would be welcome.
Cheers
Max


It will probably be a bit lossier than using Al but my first Yagi on 288
MHz(in the early 60s)was made out of 8g fencing wire and it seemed to work
reasonably well. Try the evaluation version of Eznec - I think you can
specify the material.
Alan

MMANA gives 3dB degradation for Fe over Al (11ele DK7ZB on 2m), which
surprises me. What does Eznec give ?

Brian GM4DIJ


--
Brian Howie

Brian Howie wrote:

MMANA gives 3dB degradation for Fe over Al (11ele DK7ZB on 2m), which
surprises me. What does Eznec give ?

Brian GM4DIJ

Using an 11 el DL6WU at 144.2MHz and 10mm elements, EZNEC gives gains of
14.31 dBi for Al and 14.22 for SS. With 5mm elements, it's 14.54 for Al
and 14.37 for SS.
I used a figure of 7e-7 ohm-m for the resistivity. Most stainless steels
range from 5e-7 to 7.4e-7 ohm-m.
3dB does seem excessive.
Alan VK2ADB

Max,
While there may be some degradation in gain from using stainless
steel, would it really make that much difference? I think the 'biggy'
is that you already have the stainless steel and would have to find
the aluminum. Maybe the next 'biggest' thing would be making
electrical contact between sections of that steel? A tenth of a dB
loss just ain't no step for a stepper...
- 'Doc

(all puns intended)

Alan Peake wrote:


Brian Howie wrote:

MMANA gives 3dB degradation for Fe over Al (11ele DK7ZB on 2m), which
surprises me. What does Eznec give ?

Brian GM4DIJ

Using an 11 el DL6WU at 144.2MHz and 10mm elements, EZNEC gives gains of
14.31 dBi for Al and 14.22 for SS. With 5mm elements, it's 14.54 for Al
and 14.37 for SS.
I used a figure of 7e-7 ohm-m for the resistivity. Most stainless steels
range from 5e-7 to 7.4e-7 ohm-m.
3dB does seem excessive.
Alan VK2ADB

Apparently Brian used iron as the model material, which of course is
magnetic. Skin depth is reduced, and therefore RF resistance increased,
by the square root of the permeability. So if the iron model's
permeability is, say, 100, it would increase the effective resistance by
a factor of 10.

Some stainless steels are magnetic, some are not. The magnetic ones have
much higher RF resistance than the non-magnetic ones for the above reason.

Roy Lewallen, W7EL

In message ,
Roy Lewallen writes
Alan Peake wrote:
Brian Howie wrote:

MMANA gives 3dB degradation for Fe over Al (11ele DK7ZB on 2m),
which surprises me. What does Eznec give ?

Brian GM4DIJ
Using an 11 el DL6WU at 144.2MHz and 10mm elements, EZNEC gives
gains of 14.31 dBi for Al and 14.22 for SS. With 5mm elements, it's
14.54 for Al and 14.37 for SS.
I used a figure of 7e-7 ohm-m for the resistivity. Most stainless
steels range from 5e-7 to 7.4e-7 ohm-m.
3dB does seem excessive.
Alan VK2ADB

Apparently Brian used iron as the model material, which of course is
magnetic. Skin depth is reduced, and therefore RF resistance increased,
by the square root of the permeability. So if the iron model's
permeability is, say, 100, it would increase the effective resistance
by a factor of 10.

Some stainless steels are magnetic, some are not. The magnetic ones
have much higher RF resistance than the non-magnetic ones for the above
reason.

Yes I rechecked it with 7e-7 ohm-m and 0 permeability and got a lot
better results. Moral here is don't use iron wire for antennas .

73 Brian GM4DIJ

--
Brian Howie

wrote:
While there may be some degradation in gain from using stainless
steel, would it really make that much difference? I think the 'biggy'
is that you already have the stainless steel and would have to find
the aluminum. Maybe the next 'biggest' thing would be making
electrical contact between sections of that steel? A tenth of a dB
loss just ain't no step for a stepper...

"Sorry OM, I just can't copy you.
Can you switch to a beam with aluminum elements?"

....

"CQ Aluminum, CQ Aluminum, CQ Aluminum"


Lumpy

You Played on Lawrence Welk?
Yes but no blue notes. Just blue hairs.

www.LumpyGuitar.net