Topband: dipole height

[James Wolf]

> RDF is the key point to improve signal noise, not gain. Vertical or low
dipole has very or none directivity, so low RDF or directivity does not
improve signal noise.

In general, this is the case, but it is not always true.  Consider that you
can have an antenna with a high RDF number, but at the same time has a
pattern where rear lobe positions favor the optimum elevation angles for
arriving propagated atmospheric noise.  If you look at some of the various
Low Band receive antennas and vary their parameters around, you can end up
with high RDF number with significant lobes off the back that are only 10 dB
down from the main signal.  The pattern is always a compromise and a good
RDF number is a great tool to have in the box, but it is not the only
consideration.  

Jim, KR9U