Adding another antenna to my existing antenna set-up

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Hello. I have an antenna in my attic and 2 digital converter boxes and I'm ready for the digital switchover. There are a couple other channels that I cannot get with my current antenna, and I'm considering building an antenna as shown in this video and pointing it in another direction:

http://www.youtube.com/watch?v=EWQhlmJTMzw

My question is this....how do I add another antenna to my existing system? Is it as simple as just running BOTH antennas into a splitter? A splitter is generally used to split a signal into 2 signals, but can it work the other way (combining the signals from 2 antennas into 1 signal which will go to my TVs)?
Thanks a lot!
Mike
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When I was a kid, our family home had 2 antennas on the same pole, they were just wired parallel, the TV sorted it out. That was in the days of flat 2 lead wire, but I don't see why it still wouldn't work. I'd just use a cable splitter on the pole. For the bother this will be, couldn't you just use a rotor.
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Thanks for the reply. My attic is mounted inside my attic, hung from the rafters using 2 hangers. It works like a charm, and I am afraid to move it! It's just that there is another PBS station here locally that I think might get with another antenna pointing in the right direction.
Adding a rotor would certainly be more hassle than just adding another antenna and combining the signals, wouldn't it?
The short question in all this is - can I run coax from 2 different antennas into a splitter, then from the splitter to my TV, and get signals from both antennas?
Thanks!
Mike
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They're often called splitter-combiners, and there's a reason for that.
Inside that mystery box is nothing more than 3, 5, or 7 wires connected together. The shell of the splitter-combiner serves to connect the outer shielding of the coax cable, and the center pins are connected through these wires.
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On Jan 20, 12:20 pm, snipped-for-privacy@rochester.rr.com wrote:

So for example if you had a three-way splitter with one "input" and three "outputs," you could just plug the second antenna into one of the output jacks? - H
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No, that's not the case. If it were, you wouldn't need splitters; all you'd need to do would be to connect the wires together, which won't work due to the impedance mismatch it creates.

It won't hurt anything to try it out, but ... you'll end up with problems a lot worse than what you started with. In order for power transfer to be maximized, the impedances must match that of the cable. If it's 75 ohm cable, then the splitter will contain, minimum, a set of 75 ohm resistors. The resistors allow impedance matching to the cable, maximize power transfer, and keep everything looking like the same impedance to the antenna, TV, and whatever else may be in the lineup. That's also the reason you often need to add at least a 3 dB amplifier to a line if your signal quality is minimal and you can't afford to lose any. RS carries some decent amplifier/splitters for the purpose you're talking about. They properly mix the signals from the antennas and then add a power boost to amplify the signal (but not the noise) back up to at least the level you had before you added anything to it.
I have a similar situation to yours; we're in a fringe area where the signals for DTV get pretty iffy with rain & snow or even just high humidity sometimes. Instead of another antenna though, I got myself an 80 Db variable amplifier to put on the antenna. It's a multi-directional antenna, and boy, did THAT make a difference! If the signal can get here now, I can see it<g>! I even picked up a couple more I didn't know existed. It hasn't snowed yet since I installed it, but it looks like tomorrow I'll get to find out just how successful it really was or if I wasted my money. Stupid amp cost around $60! Oh well.
Regards,
Twayne
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Most splitters, excepting the cheapie junker ripoffss will at least have resistors between the internal points such that no matter which port you measure, you will see the same resistance/impedance. That way the maximum power transfer can be maintained. If it were just wire, the impedance of the wires would be seriously mismatched, and there would be almost no power transfer to the TV set, meaning very little signal. It's the impedance matching to the cables that makes splitters work. Each splitter results in about 3 dB (half power, or half the watts) out compared to what goes in; that's the max power transfer point.
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snipped-for-privacy@rochester.rr.com wrote:

There is more to it than that.
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True; but I think it makes the point without going overboard about it.
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wrote:

...
    It would be more hassle, but it could result in a better result by eliminating some interference.
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On Tue, 20 Jan 2009 08:10:07 -0800 (PST), Mike wrote:

Yes, you can do this. You might get lucky.
You WILL introduce mutipath problems. The question is, whether the problems will be bad enough to be noticeable. If you're in or near an urban area (lots of man-made structures), its likely you'd notice more problems than if you were out in farm country.
Even though the second antenna is not pointed at the sations you get from the first antenna, it will receive some signal on those channels. The signal it gets might include a reflection off of a building somewhere. These copies of the signal arriving over multiple paths (thus the term multipath) don't add up simply. Its difficult to explain in a short message, but the bottom line is that you might improve reception for some stations, and make it worse for others. If you are looking at analog TV, you'd see ghosting as a symptom of multipath. In a digital transmission, mutipath can cause data loss. The digital tuner probably has circuitry that compensates for some degree of multipath, but if its bad enough, the circuitry won't be able to compensate fully and you won't see a picture on the affected channels.
It is impossible to accurately predict what will happen. If its easy and cheap enough for you to try it, go ahead. Worst case, you'll decide to run a second line down to the TV and use a switch instead.
--
Art Greenberg
artg at eclipse dot net
  Click to see the full signature.
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Two problems with that, and a possible fix:
Problem is, you have two outputs fighting each other; one is going to sink/source power to the other. Could result in anything from a crummy signal (weak) to no signal.
A splitter will cut the signal strength regardless of how it's used, and especially as you mention.
Look for an amplifier/mixer with two inputs and a single output if that's all the outputs you need. Then you can get a few DB boost in the signals, mix them properly, and get them to your TV. I haven't noticed anything like that at RS but have at specialty shops.
Twayne
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wrote:

Yes, you can reverse the splitter to make it combine the two signals and keep the proper impedance. The only problem is.........the two antennas may be located far enough apart that the signal induced into antenna A may be out of phase with the signal induced into antenna B. When this happens with an analog signal you may get ghosting or just a reduced signal level that would not justify using two antennas. With a DTV you may get a inferior signal level. To reduce the possibility of out of phase antennas you should try to mount them side by side so that the distance to the transmitting tower is the same for both. On the upper frequencies a half wave or 100%) phase shift is only 8 inches. On the lower frequencies it is around 2.5 feet. Keeping the antennas perpendicular and side by side is your best bet. Signal deflection from mounting the antennas inside could also cause a out of phase problem. Good luck.
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Corrected response

(to the transmitter)

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On Jan 20, 3:16 pm, snipped-for-privacy@mucks.net wrote:

But the OPs problem is (and this is probably common) he wants to pull in signals from different transmitters at different compass points. He wants one antenna 'pointed' at one transmitter, and another antenna 'pointed' at another transmitter. If you can't combine two separate antennas in this way without their interfering with one another, maybe a rotor really is the only way to do it. -- H
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I've had good luck with attic antennas.
But the tv wants to "see" one particular impedance, 50 or 75 ohms (I no longer remember. It may even have changed.)
Amateur radio types use antenna matching networks (tuners) to make sure the equipment matches the antenna impedance. You might need one of those.
Easiest of course is an A/B switch. That's what I'd do. Though it won't work with your remote.
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They're at different frequencies. I don't think they will interfere. But resistances connected in parallel are much less than either alone. You may have too much impedance mismatch to get the signal into the tv without a matching transformer.
A signal amplifier *might* do that for you, I'm not sure how they are designed.
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O

Honestly...putting dual antennas up will only give you a 3db gain if everything goes well. A 3db gain is not much when you are talking about a DTV signal.
If he is looking for a antenna structure that needs to be multidirectional that is located in the attic then he is basically entering into a non predictable situation. It would be a trial and error situation.
As you have suggested one antenna, one amplifier mounted at the antenna, and a rotor would be his best bet in the attic. Better yet would be to get the antenna outside. I suspect that one omni directional antenna without a rotor or amplifier would do just as good or better.
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If he can't get out of the attic your method will certainly work also.
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On Jan 20, 6:08�pm, snipped-for-privacy@mucks.net wrote:

digital rv converters are so cheap with coupon Op might use 2 converts one on each antenna for optimum operation
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