Hooking up two antennas

[menelfloss]

I have two antennas in my attic, hung one over the other.
When I hooked them in parallel it seemed to decrease signal strength from some stations.
I simply hooked them in tandem, with one having the little 75ohm? dohickey that hooks up to the main coax.

Is it a bad idea to hook up two antennas?
is it better to hook em up in series?

Wondering,
Mike

 

[Don_M]

This is not generally a good idea when combining antennas designed for the same frequencies/bands. It's doable, sometimes, but it takes a lot of experimentation to get things exactly right. In most situations, there's a long technical discussion about this that, in layman's terms, boils down to a paradox: "One plus one equals much less than two -- and maybe even less than one." This is particularly true inside an attic, where multipath interference can be a big issue.

The prospects are much brighter, though, when combining two antennas designed for separate bands, VHF (channels 2-13) and UHF (14-69). But it has to be done correctly. For 300-ohm antennas, it's best to put a coax transformer (aka balun, or "doohickey," if you like) on each antenna, then run coax cables from each antenna into a combiner like this one, or this one. In addition, the antennas should be separated by at least four feet and should be placed so that neither antenna blocks the other's "aperture," the three-dimensional area in front of each in which they best receive the TV signals.

 

[menelfloss]

Ah ha,
Sounds like it would be best for me to audition each antenna separatley for signal strength.
One is a VHF only the other has both VHF and UHF. That is the one I feel will be best for me online for HD content.
The VHF UHF is the most recent one that I hung up there.
Is the 300ohm transformer going to work for that one?
Do I need a different one?
Thanks so much Don for your reply.
Mike

 

[CowboyDren]

What are you trying to do? What problem do you think two antennas will solve? If you attach a post transition radar plot from tvfool.com, we could get a better feel for your problem.

 

[menelfloss]

I had an old VHF antenna and somebody gave me a uhf/vhf antenna. So I added it in the mix.
You know, the old more must be better mentality. Just wanted to know if two hooked up properly would be better or not.

I get pretty good reception but on one or two channels I get some intermitant signal from time to time.
Mike

 

[CowboyDren]

Just take the old antenna down. Don't even leave it up there, as the director and reflector rods can interfere with the ones on the new, active antenna. If you want to know why, the HDTV Primer (.com) has a lot of good stuff about antennas.

 

[Tower Guy]

I had an old VHF antenna and somebody gave me a uhf/vhf antenna. So I added it in the mix.

If all your signals arrive from the same direction, you have two choices.

Use only the UHF/VHF antenna.

Combine the two with a UVSJ.

If the signals arrive from multiple directions then more details are needed.