Topband: dipole height

[Tom W8JI]

> That's very true.  Consider the K9AY.  The RDF is about 7.7.  Compare that 
> to a 1 wavelength Beverage which is about 7.9 dB.  The K9AY has a deep 
> null in the 180 degree direction at the right elevation angle, but 45 
> degrees off that rear direction the signal is down only 10 dB.  The RDF 
> number is a W8JI creation and serves its purpose, while the DMF is an 
> ON4UN creation and also has merit, but neither of these completely 
> encompasses all the things you may need to know about a receiving antenna 
> for your location.  You have to use some common sense in junction with 
> these numbers.

If noise or QRM is randomly distributed, RDF works perfectly.

If noise or QRM is predominantly only from a rear null area, DMF works 
perfectly.

If noise is off the front, all things are meaningless.