"Bob Bob" wrote in message
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Hi Art

I'd say that every little bit helps when conditions are marginal. Even
10dB extra mean pretty well nothing in readability when the signal is
already 20dB above the noise, but a few dB *can* make a difference when
the signal is in noise.
I don't see that! would not the S/N stay the same?




Antenna efficiency and gain in the right
direction all helps but it is going to be a compromise. I mean if you want
to chat to the "locals" 30 degrees takeoff is better again!

Agreed, that is what Cecil did.


I'll admit that I havent done any huge a amount of modelling on this but
(IMO) ground conditions and height over are far more important and are
very difficult to design an antenna for all situations.

For horizontal waves the ground conditions relative to 1 wavelength is of
little concern
Height as always helps with low TOA so one has to determine the average
incoming signal angle
of choice QSO's and design to suit.
Maybe the trick
is to design your antenna for free space for "good" gain and then be able
to raise and lower it for the best angles..

Agreed but I would like to see smaller turning radius ( moving away from the
boom length mantra , )
without the necessity for dual driven stacked array This would require a
fixed feed point with
moveable elements for desired TOA to suit desired QSO..
I am sure it can be done, and since 'every thing is
known about antennas' all that is reguired is for a Guru to come forward to
share how it is done.
Regards
Art


Cheers Bob VK2YQA

art wrote:
Most people have added an amplifier only to find out that the
difference in signal
was very small. Thus many people deride the value of a 'silly' db gain
whereas DX'ers say that a single db extra is a lot !
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.
So where a dxer points to the extra 1db gain as being everything in
fact it is the lowering of the TOA that comes with the extra gain. In
my opinion if one designs his antenna for a lower TOA say 10 to 11
degrees then even tho its gain may well be below the dxers choise( a
very long boom or stacked antennas) the lower TOA with less gain will
show little difference
to the antenna of choics because the lower edge of the radiation lobe
will follow the same line and any extra gain provided will have the
same effect of adding an amplifier which is minimal compared to the
ability of capturing signals that arrive at low angles.
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.
What say ?
Art