At 11:11 AM 8/23/2006, Keith Dutson wrote:
> >It is simply not true that a larger antenna transmits better than a smaller
>one.
>
>That's a pretty broad statement to make. If so, how come all the big guns
>use very big antennas?
Tradition, mostly, which drives availability in the ham market.
Convenience and cost effectiveness for a particular system application also
drives it.
Small granularity for adding to the system (you can wind up with a stack of
3 antennas by buying one at a time spaced out in time, as budget allows).
Ease and predictability of system design (e.g. cost and schedule risk)
If one had an unlimited budget and some time for experimentation, one could
do better than the existing things that are available, and likely the
antenna itself would be physically smaller. The problem is that the value
of "doing better" is substantially lower than the available development
budget, and, there's no guarantee of success (particularly as a commercial
concern).
The other factor driving to tall antennas is the advantage you get from
height above ground, particularly in the ham "legal power limit"
context. You can't afford to give up the "ground reflection gain" by going
low. Someone operating without a power limit wouldn't be faced by this
issue, which is essentially "antenna" independent (but not "tower
independent")...
The fallacy is in comparing BIG antenna on BIG tower to SMALL antenna on
rooftop. It's the BIG tower vs Rooftop that's the killer, not the physical
antenna size.
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