Re: [TowerTalk] Gain Is a Function of Boom Length - True and NotTrue

["Jim White, K4OJ" <k4oj@tampabay.rr.com>]

My homebrew designs all center around W2PV's theorem that the boom 
should be an odd multiple of 1/4 wavelength to achieve max gain... they 
tend to be big antennas but they seem to work pretty good :-)

K4OJ



Jim Lux wrote:
> At 05:10 PM 9/10/2003 -0400, Bryan Rambo wrote:
>
> > I believe N0AX's statement to be true.  Thanks Ward!
> >
> > A corollary:
> > No amount of clever engineering in areas of element interaction, feed
> > efficiency, tuning networks (i.e. - traps), impedance matching gadgetry,
> > etc. can make up for a short boom.
> >
> > True?
>
>
> Not precisely...
> There are some fundamental limits on a combination of gain and bandwidth 
> (the classic reference is "Chu and Harrington").  You can theoretically 
> make a small, high directivity, but very narrow band  and very 
> inefficient antenna.  However, you can't get around the radiation 
> resistance problem, which makes losses a problem.  Compact loops typify 
> the problem.
>
> And, using practical materials and practical construction, losses are an 
> issue.
>
> Also, to a certain extent, smaller means less effective aperture (think 
> capture area), until you get to around 1/2 wavelength, where the antenna 
> can be physically smaller, but still has an effective aperture of about 
> 1/2 lambda.
>
> > 73 - Bryan W4WMT
> >
> > ----
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless 
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
> any questions and ask for Sherman, W2FLA.
>
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_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

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