On 11/14/2010 4:22 PM, Dr. Gerald N. Johnson wrote:
There are two causes of feedline radiation/reception -- common mode
> current and conductor spacing. A common mode choke AT THE FEEDPOINT can
> essentially kill the radiation due to common mode current unless the
> feedline is some multiple of a half wave, in which case an additional
> choke placed along the line to act as an "egg insulator" to make it less
> than a half wave would kill the remaining current.
Or if the feed line isn't perpendicular to the radiator and so gets
coupled to the radiator beyond the choke.
That's the function of the additional choke as egg insulator -- to break
the feedline into lengths (from a common mode point of view) where very
little current can flow.
73, Jim K9YC
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