[K3PZN-List] Re: J-pole question

[ke3fl at juno.com]

The J-pole antenna is fed between the two connections which form a J,
ANYTHING below the J is NOT in the equation, period. That is what makes
the J-pole such a wonderful antenna for mounting, you can mount it on
ANYTHING, wood etc or metal.

Why is that?  Well, here's a very simple idea, (Gedanken Experiment)
remember how to figure the current flow in a DC circuit? If you add a
piece of random wire to the circuit but it doesn't go anywhere, does
current flow on it? No.

In sort of the same way, an antenna has current on the part which is
"fed" between the two points in this case & extending (in this case)
up, anything below the center wire connection is ignored because the
current can see & go to the shield connection, there is no "reason" for
current to go anywhere else in that direction.

Sorry, this is very simple & leaves much out & even probably has things
"wrong" but it's not a bad way to look at it.

Hope that helps.

Oh, if you mount a ground-plane antenna on a metal pole does the metal
pole act as part of the antenna? No, for similar reasons.

73 de ke3fl
Phil K


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