On Tue, 15 Apr 2008 13:46:08 -0500, Cecil Moore
wrote:
Modeling real-world lossy stubs seems to violate
EZNEC's guidelines. How does one do it?

One does not get hyperbolic about trivialities.

..

----------------------------------------xxcenterxxx----
I_________

OR

----------------------------------------xxxxcenterxxx------
________I


73 Jouko OH5RM


Different text sizes seem to destroy the graphics, I used the medium size in
Outlook express.
Anyway the upper is OK , the lower should look like this

______________________________________/center/_____
___________I

OH5RM

On Wed, 16 Apr 2008 09:21:13 +0300, "JN" wrote:

.

----------------------------------------xxcenterxxx----
I_________

OR

----------------------------------------xxxxcenterxxx------
________I


73 Jouko OH5RM


Different text sizes seem to destroy the graphics, I used the medium size in
Outlook express.
Anyway the upper is OK , the lower should look like this

______________________________________/center/_____
___________I

OH5RM


from OP
My question:
Is there any difference if the shorted end is pointing to the center or to
the tip of dipole.
Only the stub portion has two wires in parallell, the rest is only one wire.

Jouko, I noticed this thread took a detour, but I never saw anyone
actually try to answer your question. I too, am looking to see the
answer on this.

It is amazing, all this talk about a Lattin antenna, that appears to
have lots of sites talking about how it works, but no one actually
having built one or used one, and a simple "yes" or "no" would answer
your question.

I don't have the answers or the means of testing one at this time. If
you get the answer direct, please post it here.

Thanks
Buck
N4PGW
--
73 for now
Buck, N4PGW

www.lumpuckeroo.com

"Small - broadband - efficient: pick any two."

Jouko, I noticed this thread took a detour, but I never saw anyone
actually try to answer your question. I too, am looking to see the
answer on this.

73 for now
Buck, N4PGW

www.lumpuckeroo.com

Yes Buck it is often difficult to get an answer just to the question you are
asking.
Anyway very soon all snow has melted away here and then its possible to
testbuild it.

73 Jouko OH5RM

"JN" wrote in message
...
Jouko, I noticed this thread took a detour, but I never saw anyone
actually try to answer your question. I too, am looking to see the
answer on this.

73 for now
Buck, N4PGW

www.lumpuckeroo.com

Yes Buck it is often difficult to get an answer just to the question you
are asking.
Anyway very soon all snow has melted away here and then its possible to
testbuild it.

73 Jouko OH5RM

Hi Jouko

I thought Richard's statement that modeling would tell you about how the
design might perform, was good advice. If you use EZNEC, I'd be willing to
help you if you dont already know how to use it to model your antenna.

Jerry KD6JDJ

On Wed, 16 Apr 2008 17:01:24 +0300, "JN" wrote:

Jouko, I noticed this thread took a detour, but I never saw anyone
actually try to answer your question. I too, am looking to see the
answer on this.

73 for now
Buck, N4PGW

www.lumpuckeroo.com

Yes Buck it is often difficult to get an answer just to the question you are
asking.
Anyway very soon all snow has melted away here and then its possible to
testbuild it.

73 Jouko OH5RM


Repeated message seeing that you both missed it:

On Tue, 15 Apr 2008 21:44:02 +0300, "JN" wrote:

I understand that you would suggest 90 degree?
But does it really matter?

Hi Jouko,

At right angles, yes. Does it matter? That depends on proximity to
other conductors, including itself if you "coil" it around the
radiator, or along the radiator.

When I looked at your first posting, I was confused by the single
wire, and the text graphics should have been done in fixed font.

Keep the line conductors at least 3, preferably more, wire diameters
from the radiator or themselves. Use the largest diameter for the
multiplier of 3 (or more).

73's
Richard Clark, KB7QHC

73's
Richard Clark, KB7QHC

Richard Clark wrote:
Cecil Moore wrote:
Modeling real-world lossy stubs seems to violate
EZNEC's guidelines. How does one do it?

One does not get hyperbolic about trivialities.

Is 24 dBi omnidirectional gain from a vertical
antenna enough to "get hyperbolic about
trivialities"?

http://www.w5dxp.com/SUPRGAIN.EZ
--
73, Cecil http://www.w5dxp.com

HI
Theory says that whatever condition exists at far end of 1/4 wave
stub will
appear at fed end. ie. if far end is left open a high impedance will
appear at fed end, at resonant freq. So it would appear that the
shorted end should be nearest
to feed point of antenna. The centre of dipole or bottom of a
vertical.
Hope that makes sense!................................Rod EI3CZ

I thought Richard's statement that modeling would tell you about how the
design might perform, was good advice. If you use EZNEC, I'd be willing
to help you if you dont already know how to use it to model your antenna.

Jerry KD6JDJ


Jerry, thanks for the offert.
I dont know how good these modelling programs are in this situation.
But if it is easy, so could somebody do the following:

Take 20m of wire, that is half of a dipole.
Put a 1/4 electric wavelength shorted stub for 10,1MHz so that the open end
is 7,25m from center and the shorted end pointing to the tip of antenna. One
side of stub is the 20m wire itself, like in the upper picture. Ignore all
velocity factors to make it sinple.
Now tell me what are the resonance frequencies of that kind of element and
if possible feed point impedande (80m and 30m)

I know I could do it myself but as you know learning to use a new program
reliably takes lot of time.

73 Jouko OH5RM

wrote:
Theory says that whatever condition exists at far end of 1/4 wave
stub will appear at fed end.

That's true for an ideal 1/2WL stub but for an
ideal 1/4WL stub, an open at the far end will
appear as a short at the feed end and a short
at the far end will appear as an open at the
feed end.
--
73, Cecil http://www.w5dxp.com