On Mon 28 Jul, Jerry wrote:
> There was some good talk on antennas a few weeks back.
>
> Assuming someone wants a simple quarter wave antenna (dare I say whip).
> Is the radiator material critical?
> Is the radiator wire diameter critical?
> Is the method of attachment of the Co-ax to the radiator critical?
> Am I correct in believing that an airband antenna is best kept vertical?
> Do bent antennas (like Gulf Coast's AV-534) loose much?
> Is the position of the bend critical?
> I guesse the last can be tried with an SWR?
>
>
> Interested in real solutions.
> Hypothetical postulations of losses of 0.1 % are probably not crucial in my
> rather less than perfect world.
>
> regards
>
> Jerry
The answers are:-
No,
No,
Has to be correctly impedance matched...but the physical connection is
irrelevant,
Yes (but largely theoretical),
Not a lot,
No,
Correct..
On a semi serious note the air band at 108-130 MHz is very close to both the
marine
band
and the amateur 2m band (144MHz). The technologies used there are broadly
similar
and are well documented..as are the issues and problems. The main event is that
aircraft comms are about 30 years behind the rest of the universe.
peter also known as G6FTE (thats a radio ham)..not a low flying aircraft!
Peter Bondar at home, also known as: SVP, Technologies and Engineering, Acorn
Group
tel +44 (0) 1638 552831;
fax +44 (0) 1638 552941;
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