Thread: sgc dipole?
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Old May 24th 06, 04:58 PM posted to rec.radio.amateur.antenna
 
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Default sgc dipole?

I was thinking along the same lines as Jon, LA4RT when I posted my
comment... using an 80m dipole on 40m, maybe you want to move the
feedpoint away from the current node.

How about this. If you make one leg 5% longer than the other: The
length of leg 1 is L, the length of leg 2 is 1.05L. What do you need
to have an integer number of half wavelengths on each side of the
feedpoint? (This is the only time you can get a mid element current
node, right?)

L=m*lambda/2
1.05L=n*lambda/2

= 1.05(m*lambda/2)=n*lambda/2

The lowest integers that satisfy this: n/m = 105/100 = 21/20.

So until you hit 21 halfwaves on one side and 20 halfwaves on the
other, I think you don't have a current node at the feedpoint.

Is this desirable? I think it probably is, but I am not a tuner
expert.

73,
Dan