[TenTec] was OT: Indoor Antenna: re B&W type terminated dipoles

[Rsoifer at aol.com]

Theoretical efficiency is usually figured as if the antenna is in free  
space, but of course it isn't.  Height above ground, ground  characteristics, 
surrounding objects, etc., all must be taken into  account.
 
73 Ray W2RS
 
 
In a message dated 12/7/2010 3:12:29 P.M. GMT Standard Time,  
geraldj at weather.net writes:



On 12/7/2010 5:58 AM, Jim WA9YSD wrote:
>
> Any  antenna for that matter looses 1/2 their power or more when operated 
on  a
> band that it is not designed for.

Why do you say that? I  don't agree. It may not radiate in the direction 
it did on the  fundamental. The system may loose power from matching 
network losses when  the impedance is obnoxious to match, and the really 
short antenna looses  radiation efficiency.
>
> Efficiency for a folded dipole has a  factor of around 0.98
> Efficiency for the common dipole is about  0.1

Nah, there's no reason the common dipole should be poorer than the  
folded dipole.

> Efficiency for the Double bazooka is about  0.89

Balderdash. The double bazooka is no better than a folded dipole  and has 
no significantly greater bandwidth except what comes from the  fatter 
radiator ends of shorted together twin lead. It suffers from having  tiny 
conductors encased in insulation that make it structurally weak in  wind 
and ice. If cross connected at the center instead of the original  series 
connection, the two quarter wave coax stubs do compensate for  reactance 
changes and give that variation a greater impedance bandwidth.  But its 
still wimpy and breaks all the time in the real  world.
>
> Efficiency for the above cases is its ability to  couple.  So your use of 
the
> word efficiency must be defined  better so it is not so confusing as to 
what
> exactly your talking  about.
>
>
> Stay on course, fight a good fight, and keep  the faith.  Jim K9TF/WA9YSD
>
>  -----------------------------------------------------
73, Jerry,  K0CQ
_______________________________________________
TenTec mailing  list
TenTec at contesting.com
http://lists.contesting.com/mailman/listinfo/tentec