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.
_______________________________________________
Topband reflector - topband@contesting.com
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