Anecdotally, the cages are quieter (less electrical noise) than standard
dipoles. Don't make this statement on here however, because 9 folks will
jump out of the woodwork to tell you how wrong you are.

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What few anecdotes I have read fail to say whether the noise is locally
generated or is the more distant stuff which comes in with the wanted
signals.


There is no possible reason why a fat wire will discriminate better between
between signals and distant noise than a thin wire. To any antenna
everything is just e.m waves. Receiving and radiating patterns, radiation
resistance and efficiency are identical for both.


But local noise sources are within the near field of the antenna. Or the the
antenna can be considered to be within the near fields of a lot of noise
sources.


One end of the antenna can be nearer to some noise source(s) than the other
end. So although the dipole may be accurately balanced relative to ground
(almost certainly it isn't) it may be very unbalanced relative to the
location of local nise sources.

The much greater capacitance of a fat antenna to ground, and to everything
else, will shift the local receiving pattern. The fat antenna will also
have a smaller capacitative reactance to ground and to everything else.
Remember local noise is mainly due to its electric field and so the fat
antenna, all other things remaining unchanged, will have a greater tendency
to decouple itself from local electric noise fields.

The effect is not un-related to screened receiving loops. It will be more
noticeable with decreasing frequency and with decreasing antenna sizes. It
will not be noticeable at all at low noise receiving sites where the
near-fields of the antenna and noise sources do not inter-react.
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Reg, G4FGQ