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open wire feeder, spacing of conductors

May 28th 2014, 19:09


Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
looking for the formula, or rule if you will, regarding the spacing of
conductors in a home brew open wire feed. i seem to recall that it is a percentage of wavelength.
Jun 3rd 2014, 15:59


Super Moderator

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

There isn't a convenient formula--the acceptable amount of radiation from the feedline depends on the application. And, the amount of radiation is highly dependent on the symmetry of the installation with respect to ground.

The out of print ARRL VHF Manual suggested 1.5 inches for 6 meters--you want minimal radiation to preserve the pattern of a high gain Yagi. 6 inches is often considered acceptable for an all band doublet--which typically has a high frequency pattern that is much different from the low frequency pattern.

Zack W1VT
ARRL Senior Lab Engineer

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