Topband: Open Wire Lines - Fact and Fiction

[K9AY]

My point was simply to show that the magnitude of this loss mechanism is
miniscule...

This tiny line loss due to radiation still exists if the line is twisted.
The twist simply achieves cancellation in the far field -- eliminating
signal ingress.

K9AY
_____

> While Eric greatly overestimated feedline radiation, even Gary's more
> optimistic estimate failed to consider line layout:
>
> "The field intensity from a loop is proportional to the area enclosed
> by the loop -- in dB, that's 20 log(Area1/Area2).  Applied to the above
> analogy, radiation from a 2-inch by 1500 foot loop is -67 dB relative to a
> 750 by 750 foot loop. -67 dB corresponds to a loss of 0.0000009 dB
> (e.g. 0.2 mW out of 1 kW). That's not much radiation."
>
> If conductors of the feedline are transposed at small fractions of a
> wavelength along the line (perhaps by "twisting" the line), radiation from
> each section cancels at distances large compared to the "twist distance".