[BC] Re: Commercial Station Feeding A Translator

[RADIO DOCTOR]

On Thu, 18 Oct 2007, Al Wolfe wrote:

> I also contend that it provides a degree of gain and space diversity 
> just by having more aluminum in the air in a different space.

Maybe some antenna experts and chime in on this.  Richard Fry, are you 
on this list?  My understanding has always been that combined antennas 
function as one antenna.  Two stacked and combined yagis would extract 
energy from the same frontal area as would a larger one in the middle 
with twice the gain.  There would be no space diversity effect. 
Indeed, a lower gain antenna might be better than a high gain one if a 
broad vertical lobe were desired and gain was not paramount.

>> From: RADIO DOCTOR <lylehenry at fastmail.fm>
>>> On Wed, 17 Oct 2007, Al Wolfe wrote:
>>> 
>>> >   They called this the "echelon" antenna configuration. Besides the
>>> > almost three db gain over one antenna, you supposedly get about twenty
>>> > db additional rejection from the rear. Also gain some space diversity.
>>> 
>>> Taking issue with the space diversity part.  Antenna elements that 
>>> are combined to a single receiver become an array which has a 
>>> radiation/reception pattern with a specific center of radiation. 
>>> One element (antenna) cannot augment another unless they feed 
>>> separate receivers and a circuit decides which one is providing the 
>>> best signal at the moment.  That's the principle of diversity 
>>> reception, though I'm sure it can be stated much better.


...Lyle, FMeXtra evangelist!     Cell: 213-880-4690
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Lyle Henry, CPBE  THE RADIO DOCTOR  K9DKW/K7OO  Silver Lake/Los Angeles
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