"Buck" wrote in message
...
On Sat, 29 Jan 2005 16:45:29 -0800, Richard Clark
wrote:

On Sat, 29 Jan 2005 19:22:12 -0500, Buck wrote:

Speaking of Yagi's and gain, I know that the gain (and inversely the
bandwidth) of a yagi is increased by extending the spacing between
elements. A wide spaced gives a little more gain than narrow spaced
elements. I believe it also narrows the beam width of the signal.

Hi Buck,

This is fine.

I don't think it affects that TOA, though, except maybe by its
relationship to the ground and its surrounding terrain.

It is unlikely that anything you do in such a small footprint will
bring any geometric change that brings even a perceptible change to
the TOA. However, by simply increasing gain, the entire lobe
structure of the antenna increases (same shape balloon, but now a
larger balloon) which does impact the TOA; but not its angle, instead
more its magnitude. This, in a sense, was the comparison Roy was
drawing upon with the different examples.

In a sense, increasing the antenna gain (all other factors held
constant) would be indistinguishable from simply boosting the
transmitter gain (or adding an Amp).

73's
Richard Clark, KB7QHC


I think you and I are in agreement except for what Art believes. (see
his statement below

I believe it is time for antenna designers to concentrate less on
obtaining gain and instead concentrate more on lowering the TOA.
without the need of excessive real estate requirements.

He agrees that the antenna is better as it improves receive as well as
transmit, but I can't see the TOA being more important than the gain
unless it is really off by a long way.
But Buck that is exactly what I am talking about. Just think about what
types of antenna
can be considered a band opener. Somebody mentioned a 150 foot boom yagi
which tho
it has lots of gain it is at a low height. I suspect the lobe it is
projecting will be around 13 degrees
and the lobe will be fat suchg that the lower portion of the main lobe may
well encompass a 10 degree
signal. Another band opener will be say a three element antenna at a height
of say 150 to 200 feet.
The three element antenna is not a ground shaker but the lobe is made lower
than a normal
height antenna thus even tho the antenna is relative low gain this low gain
is directed at a low angle
say 10 to 11 degrees that can intercept signals just as the band is opening.
Another band opener is vertically stacked three element beams solely
because there is three db
gain to be had purely by stacking that can be added
to the uppermost antenna which also lowers the interception angle area by
virtue of a fatter lobe.
Now look at the band when it is well established, most antennas will now
intercept a lot of the DX signals
but at the same time many of the band opening antennas may well fail to hear
the signals as the signals
may well be coming in at a higher angle which coincides with the null
supplied between the first and
second lobe . In all of this you must take note of what Reg said in that
communicating signals must have the same hop distance which revolves around
lobe interception and not gain. If the lobe intersection of the two stations
vary by say a few hundred miles no amount of extra gain is going to make
communication possible.
I am a member of the RSGB and not the ARRL.
Regards
Art



snip.

Good luck,

Buck


--
Buck
N4PGW