[Antennas] super J-pole

25 Apr 2003 19:21:22 -0600

On Tue, 2003年04月22日 at 11:28, Mike Miller wrote:
> I'm in the process of building a 2 meter collinear J-pole.=20
> Should I make it with 1/2 wave radiating sections or .64=20
> wavelength radiators and why?

Well, there's no definitive answer here, but I'll give you my
thoughts, having built each of the antennas you have mentioned.
The longer 5/8-wave elements will give you more gain. They also
make matching a bit more difficult -- the antenna gets somewhat
squirrelly on the match, but it is definitely achievable.
The shorter 1/2-wave elements result in an antenna that scales a
bit better, according to some of the informal analysis that I've
done, but the mechanical complexity rises just a bit -- the "U"
section used for phasing is a total 1/2-wave long, rather than
3/8-wave, so it sticks out more, which can be unwieldy. However,
it appears to scale fairly well with more sections, unlike the=20
5/8-wave antenna.
Either way, you will end up with a pretty good 2m antenna.
--=20
Matt Meola AF=D8D
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