Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #11   Report Post  
Old January 16th 04, 12:41 PM
jaroslav lipka
 
Posts: n/a
Default

'Doc wrote in message ...
Richard,
My peashooter is racked. Guess that means I'm just
lurking?



Nah, it means your in your usual position, riding on someone else's shirt tail.
  #12   Report Post  
Old January 16th 04, 02:04 PM
Art Unwin KB9MZ
 
Posts: n/a
Default

Hi Gary, seems like your the only one that is interesred in antennas on this
Jerry Springer group, so an answer there is.
Piddle means to mess around with things, since I am from
East London it could well be Olde English
With regard to efficiency per unit length. It is well known that the ends of
a 1/2 wave dipole can be lopped off without any noticable difference which
can be seen by the area lost under the normal current flow diagrams, so
efficiency can immediatly improved. When shortening the dipole even more we
get a transition to a straight line current flowline inplace of the sino
soidal curve which again shows a further inefficient portion at the ends
that can be lopped of. What this then shows that we can have a higher
current distribution per unit length with the mainly efficient portion in
the center of the dipole. Now one is in position to introduce a phase change
where one can have two dipoles in the same space taken up in the beginning,
collinier in form and containing only the mainly high efficient portions of
the center of a normal dipole. I see no reason why this transition can be
followed over and over again until the radiator contains an area under the
current curve that is uniform. Transformation to spot radiation
is totaly another matter which I believe should be left to our descendents.
Since you are an experimentor I would be happy to discuss my thoughts
privately rather than take up valuable space that is required for auguments
and pea shooters
Best regards
Art Unwin


"JGBOYLES" wrote in message
...
He may well be correct if we are all lemmings.


Are they the rats that jump off the cliff into the sea? If they are, I am

not
one of them.

people who piddle with antennas are a different breed.


I experiment with antennas, but piddle? I thought in Olde English that

meant
something else.

The rest of you post was interesting, could you provide more detail?

What is
"Yagi syndrome" and lossless coupling to the transmitter?


73 Gary N4AST



  #13   Report Post  
Old January 16th 04, 03:06 PM
Cecil Moore
 
Posts: n/a
Default

Art Unwin KB9MZ wrote:
Piddle means to mess around with things, ...


My unabridged dictionary says it has a second meaning.
There are many piddling contests on r.r.a.a :-)
--
73, Cecil, W5DXP

  #14   Report Post  
Old January 16th 04, 04:59 PM
'Doc
 
Posts: n/a
Default



Jaro,
Thanks! Still batting a 1000, I see...
All wrong.
'Doc
  #15   Report Post  
Old January 16th 04, 05:32 PM
Tdonaly
 
Posts: n/a
Default

Art wrote,
With regard to efficiency per unit length. It is well known that the ends of
a 1/2 wave dipole can be lopped off without any noticable difference which
can be seen by the area lost under the normal current flow diagrams, so
efficiency can immediatly improved. When shortening the dipole even more we
get a transition to a straight line current flowline inplace of the sino
soidal curve which again shows a further inefficient portion at the ends
that can be lopped of.


Hi, Art,
The above is untrue. Efficiency only has to do with the ratio of radiation
resistance
to total resistance. Also, the idea that the only part of an antenna that
contributes
to radiation is the center part because it carries most of the current is also
untrue.
The claim probably originates from the fact that most antenna parameters can be

calculated given a knowledge of current distribution. It's a false leap of
logic
to conclude that there are portions of a half wave dipole that don't radiate,
though. Since
those areas have high changing charge densities which are associated with
changing electrical fields which..., and so on, they radiate quite well.
I don't think most amateurs want to diddle around with infinitesimal
dipoles, anyway,
Art, which is what they'd end up with if they implemented your ideas. An array
of
infinitesimal dipoles such as you're suggesting would be fun to make, but I
doubt
the wisdom of expecting increased efficiency from it.
73,
Tom Donaly, KA6RUH

(P.S. Art, I hope you don't equate disagreement with ridicule. I reserve all my

ridicule for Cecil since he can take it.)





  #16   Report Post  
Old January 16th 04, 06:20 PM
Cecil Moore
 
Posts: n/a
Default

Tdonaly wrote:
(P.S. Art, I hope you don't equate disagreement with ridicule. I reserve all my
ridicule for Cecil since he can take it.)


.... .. .... ..


Tom, I notice you have not posted your calculations for
the phase angles of those superposed phasors I presented
yesterday. Did you come up with any phase angle other
than zero and 180 degrees? Do you understand why Kraus'
phase graph for standing wave current contains only two
possible values of phase?
--
73, Cecil, W5DXP

  #17   Report Post  
Old January 16th 04, 06:37 PM
Brian Howie
 
Posts: n/a
Default

In message , Art Unwin
KB9MZ writes

Antenna engineers have become so focussed on the half
wave patterns that they have completely ignored the
low efficiency portions at the ends of a half wave
antenna.


Yes, the midldle high current bit generates the H field, but you forget
that the end high voltage bits are needed to generate the E field. The
antenna 1/4 wave physical length is needed to get these in the correct
phase.

Now it should be possible to make a compact antenna where you can
generate the H field from a current element and the electric field from
a voltage element, making sure that the 1/4 phasing is preserved between
the voltage and current. Naah it wouldn't work

Brian GM4DIJ

--
Brian Howie
  #18   Report Post  
Old January 16th 04, 06:41 PM
Art Unwin KB9MZ
 
Posts: n/a
Default


"Tdonaly" wrote in message
...
Art wrote,
With regard to efficiency per unit length. It is well known that the ends

of
a 1/2 wave dipole can be lopped off without any noticable difference

which
can be seen by the area lost under the normal current flow diagrams, so
efficiency can immediatly improved. When shortening the dipole even more

we
get a transition to a straight line current flowline inplace of the sino
soidal curve which again shows a further inefficient portion at the ends
that can be lopped of.


Hi, Art,
The above is untrue. Efficiency only has to do with the ratio of

radiation
resistance
to total resistance. Also, the idea that the only part of an antenna that
contributes
to radiation is the center part because it carries most of the current is

also
untrue.
The claim probably originates from the fact that most antenna parameters

can be

calculated given a knowledge of current distribution. It's a false leap

of
logic
to conclude that there are portions of a half wave dipole that don't

radiate,
though.

Don't make up a false augument, nowhere do I say that parts of a dipole
does not radiate, soon you will have half the neibourhood up in arms
regarding something I didn't say. As for your parlying the term 'false' so
liberaly it is clear that you were sleeping during class, but then even
those who know little of radiation can have an oponion.
So what is your vision of the future with respect to antenna and are you
doing anything to make that vision come true i.e. walking the walk.or are
your jollies gained by shooting at those such as Cecil that does have the
required knoweledge? On top of all that read carefully regarding'
efficiency' since I have qualified it as ' per unit length'
Best regards
Art Unwin




Since
those areas have high changing charge densities which are associated with
changing electrical fields which..., and so on, they radiate quite well.
I don't think most amateurs want to diddle around with infinitesimal
dipoles, anyway,
Art, which is what they'd end up with if they implemented your ideas.

Lots of words but all meaningless, I never said that I was persueing the
ultimate point radiation suggestion. I
experiment to the point that all antennas regardles of frequency can be made
such that they are rotatable in the horisontal mode which means for 160
meters inovation has to be involved to reduced such a monster such that it
can be rotated around its center point. I HVE REACHED THAT POINT AT THE
PRESENT TIME and am now looking at ways to reduce it further, but maybe the
next generation will achieve that jump.! I fully expect that somebody will
say I have violated a law of old but until then I will continue to use it on
the bands




An array
of
infinitesimal dipoles such as you're suggesting would be fun to make, but

I
doubt
the wisdom of expecting increased efficiency from it.
73,
Tom Donaly, KA6RUH

(P.S. Art, I hope you don't equate disagreement with ridicule. I reserve

all my

ridicule for Cecil since he can take it.)

I don't see why he should take it! We have lost so many talented people from
this group Tom,Gary Roy and so on
but we are still not at the point where Richard and his followers ( not
Richard Harrison ) pseudo Doktors and what ever have the forum completely to
themselves.
Regards
Art Unwin KB9MZ.....XG


  #19   Report Post  
Old January 16th 04, 06:52 PM
Art Unwin KB9MZ
 
Posts: n/a
Default

Hmmmm
They said that the idea of break dancing was an impossibility but they have
classes for same in East St Louis Students are not allowed to graduate
until thay exhibit the ability of removing a hub cap off of a moving vehicle
!
They probably have the same class in The Goebals
Regards
Art



"Brian Howie" wrote in message
...
In message , Art Unwin
KB9MZ writes

Antenna engineers have become so focussed on the half
wave patterns that they have completely ignored the
low efficiency portions at the ends of a half wave
antenna.


Yes, the midldle high current bit generates the H field, but you forget
that the end high voltage bits are needed to generate the E field. The
antenna 1/4 wave physical length is needed to get these in the correct
phase.

Now it should be possible to make a compact antenna where you can
generate the H field from a current element and the electric field from
a voltage element, making sure that the 1/4 phasing is preserved between
the voltage and current. Naah it wouldn't work

Brian GM4DIJ

--
Brian Howie



  #20   Report Post  
Old January 16th 04, 07:07 PM
Gene Fuller
 
Posts: n/a
Default

Art,

You just received two serious and legitimate responses from Tom and Brian. You
proceeded to trash each of them for their contributions.

How do you expect to get useful input if you are not willing to accept anything
that does not agree with your preconceived notions?

YOU are the one with the loaded pea shooter.

Shame on you!

73,
Gene
W4SZ

Art Unwin KB9MZ wrote:
Hmmmm
They said that the idea of break dancing was an impossibility but they have
classes for same in East St Louis Students are not allowed to graduate
until thay exhibit the ability of removing a hub cap off of a moving vehicle
!
They probably have the same class in The Goebals
Regards
Art


Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Inverted ground plane antenna: compared with normal GP and low dipole. Serge Stroobandt, ON4BAA Antenna 8 February 24th 11 10:22 PM
EH Antenna Revisited Walter Maxwell Antenna 47 January 16th 04 04:34 AM
Poor quality low + High TV channels? How much dB in Preamp? lbbs Antenna 16 December 13th 03 03:01 PM
QST Article: An Easy to Build, Dual-Band Collinear Antenna Serge Stroobandt, ON4BAA Antenna 12 October 16th 03 07:44 PM


All times are GMT +1. The time now is 11:51 AM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017