# Can I combine two antennas from opposite directions



## LilBear (Nov 2, 2019)

I have two antennas (both amplified) facing basically North and South. I get 56 channels. I would like to set up a bolt system that would let me see stations and record on both antennas from each of two TVs, even at the same time. I have tried a splitter in reverse, and a ChannelMaster JoinTenna, with no useable results. I'm willing to try two Bolts, or a bolt and Mini. Any ideas?


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## kpeters59 (Jun 19, 2007)

Yes.

I've had very good results doing that.

-KP


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## LilBear (Nov 2, 2019)

kpeters59 said:


> Yes.
> 
> I've had very good results doing that.
> 
> -KP


Which method?


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## kpeters59 (Jun 19, 2007)

Combining 2 antennas through a splitter 'backwards' in to one TiVo.

-KP


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## LilBear (Nov 2, 2019)

That did not work for me. That cancelled some channels from each antenna. Same for Jointenna. I was told it was because they were both amplified. Similar to Multipath Interference


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## kpeters59 (Jun 19, 2007)

Either remove the amps, or pad them down until it works as desired.

-KP


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## LilBear (Nov 2, 2019)

kpeters59 said:


> Either remove the amps, or pad them down until it works as desired.
> 
> -KP


Can't remove amps. JUST getting enough signal with them. Thats why I'm asking for help. 43 miles South, 56 miles North


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## pldoolittle (May 2, 2002)

Mix, then amplify.


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## kpeters59 (Jun 19, 2007)

There shouldn't be any frequency interference since they're in the same 'market', but are the physical frequencies of the 'dropped' channels close at all?

It's possible the amps are causing it, so yeah, try mixing, then amplifying.

There are band-pass antenna mixers that you could obtaine, as well.

-KP


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## series5orpremier (Jul 6, 2013)

There may be better antennas for the task than what you're using. Are any channels broadcast on VHF? (Combining works for me because all my VHF channels are in one direction and all my UHF channels in another direction and using VHF-only and UHF-only antennas makes sure I'm not combining signals from the same frequency).

Do any two channels in opposite directions broadcast on the same frequency? You need highly directional antennas, but bad luck that your directions are 180 degrees from each other because some antennas pick up gain from frequencies approaching from directly behind them. If that's the case that both oppositely pointed antennas pick up some of the same channels, then combining their out of phase signals on the same frequency can cause that multi-path cancellation.

I'm not informed on which antennas are good at blocking out gain from signals approaching from behind.


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## LilBear (Nov 2, 2019)

I have tried several antennas, all with the same result. What I thought might work is to feed one Bolt with each antenna, then network them together. Has anybody tried that? Could I watch live broadcasts from one to the other Bolt? My purpose in asking you is to avoid buying a second Bolt, then find out that my theory does not work.


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## LilBear (Nov 2, 2019)

series5orpremier said:


> There may be better antennas for the task than what you're using. Are any channels broadcast on VHF? (Combining works for me because all my VHF channels are in one direction and all my UHF channels in another direction and using VHF-only and UHF-only antennas makes sure I'm not combining signals from the same frequency).
> 
> Do any two channels in opposite directions broadcast on the same frequency? You need highly directional antennas, but bad luck that your directions are 180 degrees from each other because some antennas pick up gain from frequencies approaching from directly behind them. If that's the case that both oppositely pointed antennas pick up some of the same channels, then combining their out of phase signals on the same frequency can cause that multi-path cancellation.
> 
> I'm not informed on which antennas are good at blocking out gain from signals approaching from behind.


Good thinking - but I have VHF and UHF in Both directions.


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## LilBear (Nov 2, 2019)

kpeters59 said:


> There shouldn't be any frequency interference since they're in the same 'market', but are the physical frequencies of the 'dropped' channels close at all?
> 
> It's possible the amps are causing it, so yeah, try mixing, then amplifying.
> 
> ...


That is a good theory, but the amps are preamps at the antennas, and have to be powered directly, before the mix.


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## kpeters59 (Jun 19, 2007)

Then get different amps?

-KP


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## kpeters59 (Jun 19, 2007)

There isn't any reason you couldn't use 2 TiVo's, but Live TV doesn't work between them. A Mini would, but isn't zero effort to switch between Hosts.

You could Multi-Room Stream a Recording, though.

-KP


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## LilBear (Nov 2, 2019)

kpeters59 said:


> There isn't any reason you couldn't use 2 TiVo's, but Live TV doesn't work between them. A Mini would, but isn't zero effort to switch between Hosts.
> 
> You could Multi-Room Stream a Recording, though.
> 
> -KP


Thanks for your help. Sorry to hear about not being able to share live between units. You can tell I've been working at this a while


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## wmcbrine (Aug 2, 2003)

This is more or less my system -- one antenna pointed at D.C. and one at Baltimore, not quite 180 degrees apart, but close. It was set up professionally, and admittedly, I never tested the antennas separately, so I don't know that I'm not losing any signal vs. what I could theoretically get that way; but it works pretty well. The signals are combined, no pre-amps, and the combined signal goes to a distribution amp/splitter.


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## LilBear (Nov 2, 2019)

Thanks to everyone for your help. Looks like the way I'm hooked up now is the way I have to stay. I have a Bolt on the South feeds, and the North feeds come in directly to TV. I can record South, but not North. South has many more channels, so I guess that's the best I can do. Was hoping to add recording to North, because that has the newscasts we Prefer. DTV commitment will soon be done, and I'm planning to send them packing


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## series5orpremier (Jul 6, 2013)

TiVo usually has discounts Thanksgiving week so with a deal on an (refurbed Roamio?) OTA you could also record North.


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## Narkul (Nov 7, 2004)

Make sure the antennas are far enough apart from each other, at least 4 ft ideally. Make sure the cables running from each antenna to the combiner are exactly the same length to help reduce phasing. Phasing would have caused ghosting on old analog reception, but causes dropout on digital as the tuner has problems locking onto the signal. Phasing is likely the issue, and you may not be able to easily overcome it if both antennas are sending strong signals for same channels. You could also try adding an LTE filter to block the neighboring cell phone band.


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## snerd (Jun 6, 2008)

LilBear said:


> Can't remove amps. JUST getting enough signal with them. Thats why I'm asking for help. 43 miles South, 56 miles North


The backward splitter weakens the signal by about 3.5dB from each antenna. That reduces the received power to 44%. So, weak signals become weaker when using a splitter as a combiner.


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## snerd (Jun 6, 2008)

series5orpremier said:


> (Combining works for me because all my VHF channels are in one direction and all my UHF channels in another direction and using VHF-only and UHF-only antennas makes sure I'm not combining signals from the same frequency)


For those who are lucky enough to be in your situation, a 15-2586 VHF/UHF diplexer has lower loss than a splitter, and completely avoids phase/multipath issues.


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## kpeters59 (Jun 19, 2007)

There's higher quality units than that. I'm pretty sure Holland has one. If you're combining UHF and VHF. VHF for TV is becoming pretty rare.

-KP


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## ggieseke (May 30, 2008)

There will be a lot more stations in the VHF high band after the repack finishes.


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## Mikeguy (Jul 28, 2005)

kpeters59 said:


> There's higher quality units than that. I'm pretty sure Holland has one. If you're combining UHF and VHF. VHF for TV is becoming pretty rare.
> 
> -KP


Really? They look to be the same as always for mainstay OTA TV.


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## ke3ju (Jan 5, 2004)

snerd said:


> The backward splitter weakens the signal by about 3.5dB from each antenna. That reduces the received power to 44%. So, weak signals become weaker when using a splitter as a combiner.


Actually not true, splitting the signal weakens, combining does not, as long as all channels are on different frequencies. We do this all the time in ham radio.

Sent from my SM-N960U using Tapatalk


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## kpeters59 (Jun 19, 2007)

Mikeguy said:


> Really? They look to be the same as always for mainstay OTA TV.


I suppose I should have been more clear, but I'm not sure which of my points you're questioning.

Surely it must be the 2nd as there really can't be any question about the quality of a Radio Shack splitter, can there?

-KP


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## Mikeguy (Jul 28, 2005)

kpeters59 said:


> I suppose I should have been more clear, but I'm not sure which of my points you're questioning.
> 
> Surely it must be the 2nd as there really can't be any question about the quality of a Radio Shack splitter, can there?
> 
> -KP


LOL, yep, I meant the second. Isn't VHF still pretty much a staple for OTA TV?


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## kpeters59 (Jun 19, 2007)

I was under the impression most everything was moving to UHF, but GG says there will be plenty in upper VHF...

-KP


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## snerd (Jun 6, 2008)

ke3ju said:


> Actually not true, splitting the signal weakens, combining does not, as long as all channels are on different frequencies. We do this all the time in ham radio.


Actually true.

A splitter is a 3 port passive device for which reciprocity applies. This implies that the 3.5dB loss experienced when power flows into the IN port and out of either OUT port will *exactly* match the loss when power is flowing in the opposite direction.

Internally, a 2-way splitter is constructed from a four port directional coupler that has one (reverse direction) port terminated internally. So, when power flows backwards through the splitter, about half the power goes to the IN port while the other half is dissipated by the internal termination.

Also easy enough to prove experimentally.


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## snerd (Jun 6, 2008)

kpeters59 said:


> There's higher quality units than that. I'm pretty sure Holland has one. If you're combining UHF and VHF. VHF for TV is becoming pretty rare.


You are probably thinking of the Holland DPD2 or STVC models. Those are used to separate and/or combine satellite frequencies on the SAT port with everthing below about 806MHz on the VHF/UHF port. The Radio Shack VHF/UHF diplexer is used to separate and/or combine VHF from one source with UHF from another source.


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## kpeters59 (Jun 19, 2007)

I was not...

UVSJ UHF VHF Separator Joiner HOLLAND Electronics UVSJ

-KP


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## ke3ju (Jan 5, 2004)

snerd said:


> Actually true.
> 
> A splitter is a 3 port passive device for which reciprocity applies. This implies that the 3.5dB loss experienced when power flows into the IN port and out of either OUT port will *exactly* match the loss when power is flowing in the opposite direction.
> 
> ...


I


snerd said:


> Actually true.
> 
> A splitter is a 3 port passive device for which reciprocity applies. This implies that the 3.5dB loss experienced when power flows into the IN port and out of either OUT port will *exactly* match the loss when power is flowing in the opposite direction.
> 
> ...


Hmm...I'm gonna have to tear one apart and look at it. My understand is it's just a 1.41:1 unun (unbalanced to unbalanced impedance transformer) with the 1.41 turn to the single side, and 1 turn to the split side keeping the impedance at 75 ohms. What happens if you connect the two 300 ohm outputs of each antenna and then run it through the 300 ohm to 75 ohm balun into one wire? It does get interesting when working with log periodics rather than single band yagis.


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## snerd (Jun 6, 2008)

ke3ju said:


> I
> 
> Hmm...I'm gonna have to tear one apart and look at it. My understand is it's just a 1.41:1 unun (unbalanced to unbalanced impedance transformer) with the 1.41 turn to the single side, and 1 turn to the split side keeping the impedance at 75 ohms. What happens if you connect the two 300 ohm outputs of each antenna and then run it through the 300 ohm to 75 ohm balun into one wire? It does get interesting when working with log periodics rather than single band yagis.


Perhaps we're talking apples vs. oranges. I'm talking about regular 2-way splitters such as this Holland GHS-2PRO-M that is 75 ohms at all ports.


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## snerd (Jun 6, 2008)

kpeters59 said:


> I was not...
> 
> UVSJ UHF VHF Separator Joiner HOLLAND Electronics UVSJ


That page says "Discontinued" and 0 stock.

I'd be happy to recommend the UVSJ if it were readily available on Amazon or ebay, or anywhere else that keeps it in stock. You can bag on the Radio Shack part if you like, but at least it has the redeeming feature that it is still available.


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## ke3ju (Jan 5, 2004)

snerd said:


> Perhaps we're talking apples vs. oranges. I'm talking about regular 2-way splitters such as this Holland GHS-2PRO-M that is 75 ohms at all ports.


I'm pretty sure its Apples to Apples. These are some diagrams I found poking around on Google for a few minutes.


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## CIR-Engineering (Sep 24, 2017)

LilBear said:


> I have two antennas (both amplified) facing basically North and South. I get 56 channels. I would like to set up a bolt system that would let me see stations and record on both antennas from each of two TVs, even at the same time. I have tried a splitter in reverse, and a ChannelMaster JoinTenna, with no useable results. I'm willing to try two Bolts, or a bolt and Mini. Any ideas?


If your towers are nearly 180 degrees from each other, I would suggest trying an 8 bowtie antenna with the reflector removed. This will allow the antenna to pickup stations from both directions with the least negative impact on the signal.

Or something similar. Chanel Master and Wingaurd used finale better ones...
https://www.walmart.com/ip/Antennas...MIkem_n9Pb5QIVyEXVCh1YsgTcEAQYByABEgLiB_D_BwE

Just remove the screens from the back and see what you get.

Good luck!
craigr


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## joshuacollier (1 mo ago)

In this article, I guided combining two antennas using a splitter to get better reception.


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