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What TV Aerial Splitter Should You Use

When using one antenna for multiple TVs you need to use an aerial splitter to split the TV signal. In the United States we typically use coaxial cable to install TV antennas. I demonstrated this when installing a Mohu Sky 60 and again when I posted how to ground a TV antenna.

Coaxial Splitter for Antennas

Depending on your installation you may need to make use of a coaxial splitter to run the signal to various TVs within your house. The three things to consider when choosing a coaxial splitter to split your antenna signal are frequency, attenuation (or dB loss), and the number of outputs.

Antenna Splitter Frequency

Splitters all have a frequency rating. This is shown in megahertz (MHz). It’s a measure of the frequency bandwidth that is able to pass through the splitter. In North America, the highest TV frequency is transmitted at less than 1000 MHz. Therefore the splitter you need should be rated for 1000 MHz in most cases. You can get away with 900 MHz, as long as there is not channel higher than “83” in your area. This TV frequency chart shows that channel 83 transmits at a frequency of 890 Mhz.

Antenna Splitter Loss

Many things cause loss to the TV signal, including splitters. To get an understanding of how a splitter affects your signal, we need to gain a little understanding of what noise margin is. When you use a site like TVFool to gain an understanding of the TV signals in your area, they provide you with a noise margin. I like working with this number because it provides a value that indicates how strong a signal is above it’s operating threshold. In other words, if the noise margin is above 0 after the TV tuner processes the signal, then you can see the picture.

Noise margins are typically given in decibels (dB). Decibels are not on a linear scale. They are logarithmic. Therefore when you loose half your signal power the loss is only about 3 (dB). If you are interested on how that works out mathematically, I recommend looking into the half-power point.

This is why when you look at a 2 way coaxial splitter you see a loss of -3.5 dB on each port. The 3 dB accounts for the half power loss, and the .5 dB accounts for the loss due to cable connections. When arranging 2 splitters to make 2 outputs you will get 2 outpus with a 7 dB loss and one with a 3.5 dB loss. The reason is illustrated in the diagram below.

This brings me to my next point.  It’s typically best to use a balanced splitter when utilizing an odd number of outputs. For example, an unbalanced 3-way splitter will have 1 input and 3 outputs. However, the internal workings of the splitter behave as though you’ve connected two 2-way splitters together. Therefore you will see two outputs with -7 dB and one output at -3.5 dB. A balanced 3-way coaxial splitter will show about 5.8 loss across all 3 outputs. Some of the more high end 3-way splitters can get the loss even lower.

The Number of Coaxial Splitter Ports

Now that we understand how the number of ports  on a coaxial splitter affects the TV signal it only makes sense not to buy a splitter with an abundance of outputs when you don’t need them. Whether you use all the outputs or not, the loss listed on the splitter is the loss your TV signal will receive. I tend to always purchase balanced splitters with the exact number of ports that I need. When I need to add another line, I simply upgrade the splitter to accommodate the addition number of ports.

Which Coaxial Splitter to Buy for OTA

As long as the splitter is balanced, most any splitter that can handle a 1000 MHz frequency will do I personally use the CMC brand pictured below

If you are concerned about dB loss or need to install more than three TVs, you may want to consider a distribution amplifier (pictured below). This will not only split your signal, but boost it to compensate for the loss caused by the splitter. Furthermore there is still a gain in signal power coming off each output. On the distribution amplifier I recommend (shown below), there is a +7 dB gain coming off each output. This comes in handy to overcome the noise in the coaxial cable, connectors, and TV tuner (which averages a loss of about 6dB).

Be aware that an amplifier isn’t going to boost a signal more than what was received from the antenna. It will only compensate for loss in the line from the antenna to the TV. Furthermore, if a signal is too strong it could have an adverse affect on reception.

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Categories: Guides
Dennis Restauro :Dennis is the founder of Grounded Reason. He also hosts the Grounded Reason Podcast. Follow him on Twitter: Follow Dennis on Twitter

View Comments (40)

  • Something to consider: if you are using a MOCA network, like a TiVo & a TiVo Mini, your splitters should be rated for 2GHz or 2.5GHz, to accommodate the MOCA network signals.

    • Tom, your antenna installation is going to be completely separate from any MOCA network. It's going to be ATSC from the antenna to the TiVo OTA. The article is for those without cable. The only MOCA a cord cutter will have is from the provider to the modem. It's then switched to TCP/IP for internal networking. A Cord-cutter is typically going to operating over Ethernet or WiFi where coaxial won't even be involved. Your point makes sense if you still have cable, but then why have an antenna?

  • Dennis, I really like your blog. I am a fringe user (level terrain) and have a Solid Signal HDB91X Yagi style antenna, am 55 mile from my stations (only a 8 degree spread), and have an antenna hgt. of 14' mounted inside an attic. I'm running RG6 to one TV 35' away. Without a pre-amp my CM DVR shows 100% signal quality & 30-70% signal strength, Any suggestions on a pre-amp? I actually have two of these setup side by side (3' center to center). Central Ohio

    • Winegard makes some good preamps with decent gain and low noise. I think you can get them through solid signal.

  • We built our home with coaxial ports throughout the house. I assume there are splitters inside the walls but when I tried to send signals from an indoor antenna to two tvs I could not make it happen. I needed to buy a 2nd indoor antenna for the 2nd TV. What is my problem? With cable 3 different TVs received the signal from the cable box without difficulty.

    • It would be hard to diagnose the issue without a layout of your coaxial install. I will say that it's tough to get good results splitting an indoor antenna. There is already a lot of loss from the signal coming into the dwelling.

  • I am using an RCA 10db amp, vh140N from Lowe's. 4way. Works fine. $22. Any difference from the one you suggest?

    • RCA makes decent amps. If it works, it works. I just suggested equipment that I've had good experiences with. I'm sure there are a ton of amps and splitters that work just as well.

  • Hi there, I'm not sure if my message I wrote to you actually got to you, haha, ok, i'll try to be brief, we recently dumped the dish, bought a Mohu Air 60 multi-directional antenna, put it where the dish was and used the coax cable the dish company left behind and hooked it up to our new rooftop antenna (the Mohu Air 60). Then hooked that antenna to a Channel Master amplified 4-way splitter to feed the 4 TV's in our house. We should be able to get a total of 13 channels in our area, all TV stations are in the same area (same direction from our house about 15 miles away). after hooking everything up, we got varying results. 2 of the TV's get 10 of the 13 channels, 1 TV gets 6 of those 13 channels, and the 1 TV gets all 13 channels. some of the coax cables have longer runs than others so I'm guessing that is why not all TV's get all 13 channels. Do you have suggestions on what we can do to get all 4 TV's receiving all 13 channels? The Mohu Air 60 came with an amplifier which we did not install. We certainly can try that. We shouldn't have to tweak the direction of the Mohu Air 60 antenna because it's a multi-directional antenna, but we could also try that. Do you have any other ideas?? your suggestions or thoughts would be greatly appreciated!! Thank you!

    • For these type of installs I don't recommend using existing wiring. It's difficult to know if it's optimal for receiving antenna TV. I recommend adding one TV at a time to isolate where issues may exist. I outline what to do in this post.

      Sorry if I didn't get back to you over email. I try to answer all of them, but I've been getting so many lately that some have been slipping through the cracks. I always answer comments on the blog first before getting to email questions, so it is always better to leave a comment asking a question then writing an email.

  • I really am discouraged on this fios thing , I had brighthouse thru cable box in only one room , as it got two expensive I changed to frontier , Now i cannot receive my cable thru coaxial in other rooms? Do you know if they reconfigure the signal some how where Now I cannot receive ???

    • David,
      Frontier: You can run HDMI into another room and into TV, if multi, used HDMI Hub, and send TV Signal to another TV, however, with Dish, remote works in another room, but with Frontier, unless you run wire for RF booster you won't be able to control your stations or the box in another room (you'll have to go to that room).

    • They will most likely want you to have a box for each TV. That's how most pay TV companies work. It's one of the reasons I cut the cord.

  • I'm using a channel master masterpiece 100 with a CM7777 and an CM ultra mini 4. I'm puzzled as I'm receiving channels like 2 (shown as -4.1 and 107.5 Miles away) and 51 (shown as -6.9 and 96.4 miles away) but I have a hard time receiving 4 (shown as -2.8 and 111.9 miles away) and 7 (shown as -5.9 and 113.4 miles away).
    The signal is less on 51 yet it's constant, yet 4 & 7 seem to come and go. I have and am making arrangements to go higher, yet the TV Fool says I'm going to get more loss on some channels by going higher? That's puzzling if I'm trying to get over edges? 23 & 51 are both received currently over 2 edges. So why the difference on 4 & 7 if they both have higher signal strengths? I'm considering putting in RG11 from the tower to the internal amps but the run is only 60-70 feet so I don't know if the signal gain is going to be significant in resolving the instability? Seems only a .5-.9 db gain on a 100 ft so I don't know if that will be a significant increase in signal. Ideas???
    I know I'm doing well considering the distances, but I'm trying to understand how 51 with it's -6.9.

    • Hard to say without seeing the report. What is the real channel for 4 and 7. Are they on UHF?

  • Dennis - I live in Duluth, GA - about 20 miles north of Atlanta. What indoor digital antenna do you suggest? Antenna with amplifier? I'll be connecting 3 or 4 TV's - use correct 4 way splitter OR a 4 way distribution amplifier? Any other tips will be greatly appreciated. Thank you - Doug

  • I needed an OTA antenna to get locals when satellite signal goes out. I placed a directional antenna in garage high in rafters, as other than roof/shingles, no other obstructions. TVFool reports 5 channels (and so does my TV), which is fine, with Noise Margins ranging from 60.2 to 30.0 (I tried to paste in a screenshot but couldn't). Same distance to tower (19.5 mi), same Magn direction, same mountain. The interesting thing is that only 4 channels have a signal strong enough to display, and one doesn't and the curious thing is that the 'middle' channel, based on NM is the one that won't display. Why would that happen?
    Set up is 1980's builder's coax into central area of house from garage, probably 75 feet at which point I feed a powered amp that came with antenna that then directly feeds a 2 way splitter (again, 1980's item) and then output to 2 TVs using RG6, running about 40 feet to 1 TV and about 15 to 2nd. My primary TV (40 ft run) is my test case. I get a 'bearable' signal on the weak channel if I use no splitter (no luck with 1 leg of splitter used along with a terminator on the other output). Other 4 channels look really good. 'Real' channel designations are 22, 14, 13, 32, 43 with 13 being the problem.
    So,
    1) why does middle strength channel (41.3 NM) not come in when weaker stations seem to?
    2) would a different splitter or amp (placed where?) help without overdriving my stronger signals?
    Replacing coax from garage would not be very easy. Appreciate any insight/suggestions. Thanks.
    Paul

    • I would need to see the report. If you past the link I could take a look.

  • Hello. All cable splitters have what looks like a ground screw. When is it necessary to make use of this?

    • It's never a bad idea. However, the need is especially important when there is the possibility of lightning strikes.

  • What kind of splitter do I need to hook two roof top antennas together and send the signal into the house on one coaxial cable?

    • I don't recommend doing that unless you are using a Band filter. They allow you to set one antenna to pick up VHF and the other to pick up UHF. The one I'm familiar with is discontinued but you can just search for "UVSJ signal combiner" to get an idea what is available.

  • Hey Dennis, I live(New London 28127), on average, about 45 miles away from a few towers, with the towers in an almost 180 degree opposite directions. But I am just focusing in on the towers in one direction, which is the Charlotte NC direction. Hooking up an AntennasDirect 2V in my window temporarily and into the back of just 1 TV, I can pick up about 32 channels. I am mounting this antenna outside and will require new cables to connect to it and to two TV's. Cable distance from OTA antenna to 2 port splitter is 55'. Distance from TV1 to splitter is 25' and distance from TV2 to splitter is 11'. Will there be any benefit from using RG11 cable as compared to RG6 cable, in my case? Best/strongest station has NM(dB) is 45.2 with PWR(dBm) of -45.6. Would an amplified 2port splitter be overkill?

    • I don't think the Cable would benefit you that much. Those distances aren't going to to see much of an improvement when using RG11 over RG6. At that signal a pre-amp wouldn't be overkill.

  • Hi Dennis. I am currently using a 3-way splitter for my 3 televisoins, but have added a 4th television in the basement. My current setup goes like this: I have an outdoor 30' tower antenna which feeds into an amplifier (Provo Model PRE-75) which has one input and one output. The output from this amplifier goes into the 3-way splitter. My question is this: can I simply replace the 3-way splitter with the PCT 4 Port amplifier/splitter that you mentioned in your article above or should I use some other type of 4-way splitter that is not amplified? I guess I'm concerned about an amplified signal going into another amplifier. I guess the other thing I could do is get rid of my current amplifier which has one input and one output and replace it with the PCT 4 Port amplifier/splitter. Any suggestions on what option is best. Thank you.

    • I would use the powered splitter. You will need it to overcome the signal loss.

      • Which of the following am I replacing with the 4-way splitter: a) replacing only the 3-way splitter with the 4-way splitter and leaving the existing amplifier, or b) removing the existing amplifier and 3-way splitter and replacing both of them with just the 4-way powered splitter alone?

      • Which of the following am I replacing with the 4-way splitter: a) replacing only the 3-way splitter with the 4-way splitter and leaving the existing amplifier, or b) removing the existing amplifier and 3-wasy splitter and replacing them with just the 4-way powered splitter alone?

      • Thanks, Denis. Just to clarify and make sure I understand correctly, would I keep the existing amplifier and just replace the 3-way splitter with a 4-way powered splitter?

  • Thank you so much for putting all of this information together. I have a question about exterior antennas and splitters. I have two televisions and I want to get a roof mounted exterior antenna. If I put the antenna on the side of the house that has the unused fireplace/chimney, then I would have to install the splitter either outside or in my crawlspace under the house. On the outside it is in a pretty protected area. Installing the antenna on this side of the house gives me the shortest run to the main tv used. Is there an exterior style splitter that can take the PNW rain? If I go that route are there weatherproof connectors for the coaxial cable that I should use?

    If I install the antenna on the other side of the house, then I need a mast, and the splitter can go into the garage, but the run to the main television is about 70 feet which I understand can degrade the signal

    Again, Thanks so much for explaining to all of us that don't quite get it.

    • That's a good question. I was assuming it wasn't. The best solution would actually be an outdoor splitter box that would keep it completely out of the weather.