> Now I'm gonna feel real stupid asking this...buuuuut,
> I really would like to know...so, here goes. How come
> the formula for a half wave dipole is 468/Freq but the
> formula for a Full wave loop is 1005/Freq. I guess My
> real question is, why is the loop formula 1005/Freq.,
> and not just 936/Freq ??
The formulas for open-ended antennas like dipoles use some
rough guess for capacitance loading of the end caused by the
abrupt termination or abrupt end of the antenna conductor.
There's a little capacitance out there at the open end that
"loads" the antenna, so we "guess" how much shorter the wire
needs to be and the formula includes what we think is a
likely guess.
When it is in a loop, that capacitance is more or less
ignored because the assumption is there is no end loading
because there is no end. Of course if you had support
insulators at the HV points in the loop it would make the
loop look longer, but no one tells you that...hi hi.
Many things we use and worry about are just close guesses.
It's just a hoot when you realize this and watch how finicky
people can be when applying what really amounts to a rough
approximation. Amplifier tank Q is a great example of this,
because it is a very loose guess that doesn't mean much at
all, yet people will bust their butts to get a system dead
on to what amounts to being a rough guess.
What should you use? Whatever works for you in the end.
73 Tom
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