Hi All

Is there a web site where I can read about the relation between the
thickness of the wire and the bandwith.

Thanks in advance

73 Per OZ1EQC

Is there a web site where I can read about the relation between the
thickness of the wire and the bandwith.
================================

Antenna bandwidth changes very slowly relative to wire diameter. It is best
considered in terms of antenna Q at 1/2-wave or 1/4-wave resonance.

Approximately -

Q = 1.7 * [ Ln( Lambda / 2 / Diameter ) - 1]

where Lambda is free-space wavelength and conductor diameter is in the same
units. Ln is the logarithm to the base e.

The formula applies up the point where conductor diameter is about 1/6 of
dipole antenna length.

Knowledge of antenna bandwidth is not of great practical use at HF because
the Q of the feedline plus tuner has at least the same effect on the overall
system bandwidth as the antenna.

Download program DIPCAGE2 from website below to see how bandwidth changes
with effective diameter of a dipole cage antenna.
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.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

"Per Bekker-Madsen" wrote in message
...
Hi All

Is there a web site where I can read about the relation between the
thickness of the wire and the bandwith.

Thanks in advance

73 Per OZ1EQC


Per,

Going from 2 mm to 10 mm wire is not going to make a dramatic increase in
bandwidth. If you are trying to cover all of 75/80 meters, for instance,
with an SWR less than 2, you are better off having two parallel dipoles. You
would have to play with EZNEC to get it right, but you need the dipoles to
be resonant at roughly 3800 and 3600.

Tam/WB2TT

Hi All

Thanks to all, I have learned a lot reading your comments, was Interested in
how much difference there is in bandwith between a dipole 2 mm thick wire
and a coax antenne made of RG-213 :-)

73 to All of you

Per OZ1EQC