On Sun, 30 Jan 2005 03:09:54 GMT, "
wrote:
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.
Fair enough, I can't know where everyone is on the internet. On the
air, I get the advantage of having their callsign. I'll be glad to
send you the antenna design if you wish. (I see that isn't your
problem here).
Regards
Art
It appeared to me that you were looking for that lower lobe, not the
higher one when the band opens. The longer the beam, the narrower its
pattern is, and like better the rejection from other directions (f/b,
f/s rejection, etc. I took that as an understood.) )While answering
both you and in part, Roy,)
from the OP:
Fact is that most long distance signals on 20 metres come in at angles
of 11 degrees or less where as the 'normal' antenna has a TOA of around
14 degrees.
end quote.
I was under the impression that you felt a need for designers to find
a lower TOA. closer to ten or eleven degrees. I am confused, there
can be no doubt of that in your minds at this point I am sure
. I
do realize that at least in a yagi, as you increase the forward gain
(f/b and s/b ratios), generally by adding elements that it narrows the
forward lobe horizontally and vertically. A 150 foot boom (say 20
elements for example) beam might be perfect for picking up the lower
angle, which is what I thought you were looking for. The three
element beam will bring in higher angle signals as the lobe will have
a higher angle. A dipole will likely have even a higher, possibly a
NVIS angle. As for being quieter, I didn't define it but I mentioned
that the N4GG antenna was much quieter than my dipoles. It also has a
low angle of radiation, which fits very well with what you and Roy are
telling me. It doesn't have a high gain, in fact the designer doesn't
even try to calculate it except to say it is a little higher than a
dipole. He also said it was designed for the DX and not to expect to
chat with many nearby stations.
For a small real estate layout, I imagine that the N4GG can be used
with a dipole or small beam for continuous DX operation. Of course
the N4GG antenna is larger than a dipole. It is one wave long and has
quarter wave legs hanging off it.
.... from the OP
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.
Are you looking for a small antenna that will pick up the DX before
the other DX hounds start piling up?
--
Buck
N4PGW