[mythtv-users] Antenna amplifier

Allen Edwards allen.edwards at oldpaloalto.com
Tue Aug 5 14:33:23 UTC 2008


Jay R. Ashworth wrote:
> On Mon, Aug 04, 2008 at 09:47:28PM -0700, Allen Edwards wrote:
>> I tried combining two antennas and the results were terrible, similar to 
>> what you are describing.
> 
> Perhaps, but it likely depends on the patterns.
> 
> In Tampa Bay, where I live, we have 6 stations in Riverview, about 095
> or 100 from here, 25 mi, and *one*, WTSP, in Tarpon, about 355 or so,
> about 15 mi.
> 
> When people had antennas, everyone had 2, a one channel yagi pointed
> north, and a broadband (what do they call those again?  Oh yeah, a log
> periodic for VHF) aimed east.  Some people had combiners before their
> balun, but I know that some people just ran both pieces of twinlead
> together under the screws; I saw it.  Decent pictures.
> 
> So a lot of it is situational.
> 
> Cheers,
> -- jra
That situation sounds more hopeful as the yagi will not only have some 
off axis rejection but also off channel rejection so it will not put out 
as much interfering signal into the other channels as a broadband 
antenna would, which is probably also not as directional as well as 
being broadband.  The yagi is not going to be as sensitive to the 
broadband signal as it is looking at the stronger signal and probably 
has more gain than the broadband as well.

It may also help to have the two antennas close together, I don't know. 
  This point is, if the signals are in phase, they will add and not 
notch up the passband.  You can actually take two identical antennas 
pointed in the same direction, space them apart on the pole, and combine 
them for added gain but that is a well controlled situation.

I agree with what you say, every situation is different.

Allen



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