"Dave Platt" wrote in message
...
In article FUB1e.8710$NW5.8590@attbi_s02,
wrote:

It doesn't with my antenna where the lobe gets larger
as radiation is deflected to the forward direction.

There is a harsh limit, imposed by physics, as to how much gain that
approach can give you.
Agreed... Do you know what those limits are ?



If all of the energy from one hemisphere is redirected into the other
hemisphere, and if the forward-direction pattern shape does not change
(the forward lobe is not narrowed), then you have a forward gain of 3
dB (2:1 power ratio increase). You *cannot* have more, as this would
require that the antenna be radiating more power than it receives from
its input.

Absolutely incorrect. If I place the air of two balloons ,which reflect the
figure
eight,into one single balloon and where the laws of partial pressures do not
intervene
then you will have a balloon that is round and not elongated as the antenna
books
would have you suggest. "Gain" is a term used to to quantify a small
portion of the
energy contained in the mythical ball of energy. Since the collection of
energy comes
from different directions and phases the energy collection is layered
depending on
the influence of the earth. Thus the layers of radiation are distorted
where one layer
can be squeezed outwards further than other layers, thus the terminology
of "gain"
If you are going to interelate the terms of "gain" and "power" then you must
define
the parameters used to allow that.





A Moxon antenna is, to a first approximation, a pretty good example of
this approach - it has very little energy in the rear hemisphere, and
a broad forward lobe. There are various two-driven-element array
designs which achieve a similar pattern and result.

And the resulting "gain" is ....what?
I have difficulty in getting beyond 16 dbi as any additional energy from the
rear
has very little effect on the diameter of the frontal lobe.


Obviously with a yagi cancellation is occuring as well as addition.


You are trying to draw a distinction between "deflection" and
"cancellation" which I believe is invalid. Both are simply ways of
describing the result of the "sum of vectors" effects of having energy
from multiple radiators (driven or passive) combining in different
phases at different locations. Same math, two different words.

Yes I agree because of conservation laws e.t.c . When cancellation occurs
then energy creats energy in another direction similar to pulling steel
apart in tension
(or using compression) the steel becomes narrower before severing occurrs.
This thinning or "waisting" is created by the additional forces created at
90 degrees
to the tensile forces and where the break actually occurrs at 45 degrees
and not at right angles.

Do you know what creates the narrowing of the main lobe ?



Conservation of energy *requires* that the main lobe be narrowed, if
you wish to achieve more gain than you can get by simply redistibuting
the rear-ward energy in the forward direction.

This is what you alluded to before and it is still incorrect
What "requires" what ? And how is this conclusion generating
an elongated lobe?


A super-high-gain antenna *cannot* have a wide, uniform beam-width in
both azimuth and elevation.

Don't know how you can say that unless somehow you generated a single lobe.
Now that would be interesting




As usual for your postings, Art, it's impossible to tell whether your
claims for your antenna are plausible, because you refuse to disclose
*anything* (either the invention, or the results you claim) in any
halfway-tanglible form (e.g. models, specific numbers, etc.).


My antenna is somewhat related thus my interest in what creates an elongated
lobe
which is formed using Yagi principles.
The question however, is specifically related to Yagi's
and its narrowed lobes.
Do you know what it is that creats an elongated lobe
on a high gain yagi i.e not totally round.?
Nothing more, nothing less.
Regards
Art





Until you do, I really think it would be to everyone's relief if you'd
follow through with your recent statement that you were going to stop
posting. You're achieving no good result for yourself by contining as
you are.
I have not posted as you have inferred. The question is about Yagi design


AE6EO
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