"Dave" wrote in message
...

"John - KD5YI" wrote in message
news:uP70g.270$_s5.47@trnddc04...
Dave wrote:
How would you guys who are stuck in an endless thread of loading coils
like to take on 'linear loading'?? are the currents the same at each
end of the loading line?? do they cancel completely along the length of
the loading line? does the loading line replace so many degrees of the
length of the elements or cause some kind of delay???

As far as acting as loading element, it is another form of (real life)
loading inductance, so it is similar to loading coil, but worse performer in
the loaded Yagi situation. Have look at the end of my article
http://www.k3bu.us/loadingcoils.htm
where EZNEC plot shows current distribution along the loaded Yagi element,
using loading stubs.

the antenna i am working on is an m-squared 40m4lldd where, for example,
the reflector is 50' tip to tip, about 10' out from the boom there is an
insulator, a rod about 9' long connects with a metal bracket on each
side of the insulator and folds back toward the boom where they are
connected with an aluminum shorting bar that then uses a piece of
phillystrand that goes to an element truss support bracket. then of
course beyond the insulator is another 15' or so of element, the tips
are adjusted to tune the elements.



What's "linear loading"? What's a "loading line"?

i probably didn't do a very good job of describing it, but basically you
take a shorter than 1/4 wave element and cut it in the middle somewhere
and put in an insulator. instead of putting in a loading coil as you
would normally expect you use a shorted piece of parallel wire line to
tune it. in the case of the 40m4lldd the parallel wire line is made of
aluminum rod and is folded back to use it as a truss for the element.


It has been found and published in articles in CQ magazine, where loading
stubs were replaced by the loading coils and the performance of the antenna
like KLM 80m 3 el. loaded Yagi was improved significantly. Better gain and
better and cleaner F/B and pattern. Real modeling and measurements confirmed
that, regardless what the "flat earth - same current" believers claim and
try to "prove".
Folding the loading stubs along the elements seems to distort the current
distribution along the element and deteriorate its' performance. So you are
better off replacing loading stubs with loading coils, and that's what the
whole debate about the current distribution, reality and understanding it is
about.

73 and GL Yuri, K3BU.us