In a message dated 1/15/2001 3:27:37 PM Eastern Standard Time, aunwin@fgi.net
writes:
> The Antenna Handbook seems to strive for even HIGHER
> rejection ACROSS band which would appear that there
> is some desirability for a HIGHER level of rear rejection,
> but for whome and what level would satisfy those needs?
> Do DX's have different needs than the normal
> ham ? Is it a technical plateau preventing increases in
> this area, or is it that further increases in this area would
> be perceieved as a negative by some users?
> Art Unwin
> KB9MZ
It depends....
There are situation where F/B, F/S is not that important and max gain is
desired. I.e. for contester to have maximum signal and some splashback side
might be welcome, to keep the QRM/competition away from it's running
frequency. Most desirable property for transmit.
On the other hand, maximum cleanest pattern with minimum side and back lobes
is desirable for QRM rejection, noise rejection and improvement in S/N ratio
to be able to dig out the weakest signals out of band/QRM noise. Most
desirable property for receive.
This is why for extreme, especially low band operation combination of
vertical for transmit and sharp receive antennas (beverages, pennants...) is
the best. Puts your TX signal into wide area and allows to selectively scan
various directions with good S/N antennas.
For DXers not too important, they have time to wait in the pileup or for
conditions to swing, contester can't wait, gotta get him NOW and move on.
It boils down to trade off between real estate, money and time - that is the
limit for technical plateau. Serious contest nuts will go for the max, one
has never enough antennas or dBs. Every extra dB either way means another
layer of stations that others can't even hear and that's what wins the
contests.
So ideally, antenna that can switch between the above two modes, would be the
winner.
73 Yuri, K3BU
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