When is a balanced feedline balanced?
 

When a wire flattop is fed with parallel line, what are the affects on the
system when the feedline is not perpendicular to the flattop? It would seem
to me that the system, consisting of flattop and feedline is no longer
balanced, and the feedline will radiate on transmit and pickup local noise
on receive.

Any comments will be appreciated.

John, N9JG

When is a balanced feedline balanced?
 

John, N9JG wrote:
When a wire flattop is fed with parallel line, what are the affects on the
system when the feedline is not perpendicular to the flattop? It would seem
to me that the system, consisting of flattop and feedline is no longer
balanced, and the feedline will radiate on transmit and pickup local noise
on receive.

Essentially correct but common-mode chokes and/or
link coupling can help. And it's not just a parallel
line problem. Coax that is not perpendicular to
the flattop suffers essentially the same problem.
--
73, Cecil http://www.w5dxp.com

When is a balanced feedline balanced?
 

John, N9JG wrote:
When a wire flattop is fed with parallel line, what are the affects on the
system when the feedline is not perpendicular to the flattop? It would seem
to me that the system, consisting of flattop and feedline is no longer
balanced, and the feedline will radiate on transmit and pickup local noise
on receive.

That's correct. Common mode (unbalanced) current is induced into the
feedline by the unequal radiation from the two halves of the antenna.
This also occurs with an off-center fed antenna even if the feedline is
perpendicular, and with coax feedline.

Roy Lewallen, W7EL