[BC] Re: Commercial Station Feeding A Commercial Translator

[RichardBJohnson at comcast.net]

> 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.  

Sure they can and antenna manufacturers even make precut stacking
harnesses for such use. A signal that arrives in phase from one
antenna combines with another similar signal, resulting in twice the
signal voltage. Noise, however, combines as sqrt(2) = 1.4, so every
pair of similar antennas that form an array not only increases the signal,
but also (potentially) improves S/N.

However in the subject case, at 90 miles, the signal would have to go
through the earth and even if the TX/RX antennas were high enough
there might be Fresnel zone problems causing instability.

--
Cheers,
Richard B. Johnson
Read about my book
http://www.LymanSchool.org


 -------------- Original message ----------------------
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.
> 
>