>From: dwink@juno.com (Daniel C Winkler)
>Any integer-multiple of half-wavelengths of coax feedline will appear
>to be a HIGH impedance, and it WILL NOT radiate. A half-wave-length
>coax feedline will not radiate. Assuming you have it attached to the
>middle of a resonant dipole.
Hi Daniel, I do believe I smell a myth. We are talking about the
outside of the braid which looks just like a piece of wire to the
emerging RF from the inside of the braid. A half-wavelength of wire
repeats the voltage, current, and impedance at both ends and one
end is grounded so what impedance does the RF see? Extremely low,
lower than the antenna impedance and Ohm's law says more RF will
flow on the coax than on one side of the dipole and the coax will
radiate. One needs a balun of some sort at the antenna feedpoint to
keep the feedline from radiating. Please don't confuse the impedance
transformation on the inside of the coax with what is happening to
the wire on the outside of the braid. QRP hides a multitude of ills.
Run a KW through it, touch the chassis, and you will believe.
73, Cecil, W6RCA, OOTC
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