I'm puzzled by most of what Jim wrote.
"Efficiency" is a term well understood by most professional engineers
as: Efficiency = Pout/Pin
If we are talking specifically about an antenna's efficiency - not an
antenna *system* - the expression becomes:
Efficiency = (Radiated Power)/(Power input) = (Power input -
Losses)/(Power input)
The only losses in a simple antenna are I^2*R losses in the element(s).
If we take a resonant 20m half-wave dipole constructed from #14 wire,
its efficiency is about 98.5% (-0.06dB); if we operate the same antenna
on a different band - say 17m - the efficiency improves to 98.9% (-0.05dB).
The efficiency of a Double Bazooka will be lower than that of a
half-wave dipole because of extra losses in its coax stubs.
73,
Steve G3TXQ
On 07/12/2010 11:58, Jim WA9YSD wrote:
Any antenna for that matter looses 1/2 their power or more when operated on a
band that it is not designed for.
Efficiency for a folded dipole has a factor of around 0.98
Efficiency for the common dipole is about 0.1
Efficiency for the Double bazooka is about 0.89
Efficiency for the above cases is its ability to couple. So your use of the
word efficiency must be defined better so it is not so confusing as to what
exactly your talking about.
Stay on course, fight a good fight, and keep the faith. Jim K9TF/WA9YS
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