How to Combine Multiple TV Antennas
Introduction
In some cases, it may be necessary to use more than one TV antenna to receive all of the TV stations within a specific location. The most common reason why multiple TV antennas are used is when you are located in between two different TV markets or cities. You wish to receive TV broadcasts from both markets, but, the TV broadcast towers are in nearly opposite directions and you do not wish to use a rotator. Combining two antennas is a way to receive TV stations in both markets if they are combined correctly. There are a number of correct ways and there are incorrect ways to combine multiple TV antennas. This page will explain how to properly combine multiple TV Antennas.
Multi-Path Interference
When TV antennas are improperly combined into one coax cable, multi-path interference will occur and the TV tuner will not display the picture. The best way to understand multi-path interference is to imagine two different people talking to you at the same time. Each person is reading the same paragraph at the same speed. If each person is saying the same words at the same time, then you will understand both persons as they read the paragraph. This is referred as both persons being in sync with each other. If one person's reading is slightly slower or behind the other person than it will be difficult to understanding both persons as they read the same paragraph. This is when both person are not in sync with each other. Multiple TV signals that are not in sync are referred as multi-path interference.
When two antennas are improperly combined into one coax cable, they both "talk" to the TV tuner at the same time through the TV signal. It is impossible to have multiple TV antennas "talk" to the TV tuner and be in sync all the time. As a result, multi-path interference occurs and the TV tuner malfunctions. There are a few ways to combine multiple TV antennas into one coax cable so multi-path interference doesn't occur.
Why Combining Multiple TV Antennas Using a Backwards Coax Cable Splitter is INCORRECT
There are people who attempt to combine multiple antennas using a standard coax cable splitter. The splitter is used in a "backwards" method. Each antenna is hooked to each of the splitter's output connectors. The TV tuner is then connected to the splitter's input. In theory, using a standard coax splitter in reverse "should" combine the signals from multiple antennas. Here are the reasons why this is not an effective method for combining multiple TV antennas and why this method will most likely reduce your TV reception:
1.) A standard coax splitter weakens the TV signal because signal loss occurs at each of the splitter connections.
2.) Multi-path interference will occur because the splitter does not place the signals in sync when they are combined.
Beware of Cheap Signal Combiners and Cheap Antenna Couplers
There are several products that claim to combine several antennas into one coax cable. These products are merely a standard coax splitter repurposed and placed into a different case. These products work the same as a "backward splitter". Avoid these products. Be sure to combine multiple TV Antennas by using one of the methods listed in the article titled Proper Methods to Combine Multiple TV Antennas
Proper Methods to Combine Multiple TV Antennas
1. Combining Multiple TV Antennas Using a SmartKom Device - MSRP: $199.99
Made by Televes, the SmartKom is a device that can combine up to three TV antennas into one coax. The Smartkom does NOT combine the actual signals from each antenna. Instead, it constantly monitors the signal from each antenna and serves the best signal to your TV tuner in real time. Since the Smartkom serves the strongest signal from only one antenna, multi-path interference is never encountered. The Smartkom unit is commonly used in areas where the TV broadcast towers are in different directions. In the "old days" of over-the-air TV, households would have only one antenna. An electric antenna rotator would rotate the antenna to point toward the TV broadcast tower of interest. The rotator would be controlled from inside the house. When using the Smartkom device, multiple antennas are used. Each antenna is pointed in a different direction, aimed at each of the broadcast tower of interest. The antenna with the strongest signal is automatically sent to the TV tuner.
The Smartkom is the most expensive method to combine multiple TV Antennas. However, it is the most effective method.
2. Combining Multiple TV Antennas Using a Johansson KIT7474L2 Device - MSRP: $149.99
Made by Johansson and sold by Antennas Direct, the Johansson KIT7474L2 device works in the same manner as the Televes Smartkom device. Please read the section titled Combining Multiple TV Antennas Using a SmartKom Device - MSRP: $199.99 to understand how this TV antenna combiner works. The Johansson differs from the Smartkom in the following ways:
1.) The Johansson device has a MSRP cost of $149.99
2.) You can combine a maximum of four antennas.
3.) Does NOT work with LOW-VHF stations.
4.) You CANNOT manually program the Johansson device, The Smartkom allows manual programming.
3. Combining Multiple TV Antennas Using an External TV Tuner Device - MSRP: $30.00
One Television Using Multiple Antennas at the Same Time
You can use an external, stand-alone TV tuner along with your TV's internal tuner to combine multiple TV antennas. One of the antennas is connected directly to your television and the second antenna is connected to the external TV tuner. The external TV tuner is connected to your television by using one of the HDMI input ports. This is setup as follows:
1.) Hook the first antenna directly to your TV. Your TV's internal tuner will be used with the first antenna.
2.) Hook the second TV antenna to the external TV tuner.
3.) Hook the external TV tuner to one of the HDMI input ports on your TV.
4.) Use your TV's remote to toggle between using the internal TV tuner (first antenna) and the external TV tuner (second antenna).
You can purchase the Mediasonic Homeworx external TV tuner for about $30.00. It is a very good TV tuner and it has a DVR.
Multiple Televisions Using Multiple Antennas at the Same Time
You can use external, stand-alone WiFi TV tuners to connect multiple TV antennas to multiple TV's. This would be necessary if you have multiple TV antennas and you have several TVs in your house that you would like to connect to the same antennas. Each antenna would be connected to a dedicated Wifi, external TV tuner. The external TV tuner(s) would connect to the home Wifi. Each TV would connect to each tuner using the app. that is included with the WiFi tuners. This would be setup as follows:
1.) Antenna #1 would be connected to the first external Wifi tuner.
2.) Antenna #2 would be connected to the second external WiFi tuner.
3.) Each TV would access each TV tuner, through the Wifi, using the app that is used with the TV tuners.
4.) Each TV can toggle between each TV antenna by selecting the respective external Tuner in which the antenna is connected to.
Two, very good external TV Tuners, are the Tablo, made by Nuvyyo, and the HDHomerun made by Silicon Dust. It is recommended to use the four tuner models of any external Wifi tuner. While using the four tuner model, up to four TV's can access the tuner's antenna at the same time.
4. Combining a UHF Antenna and a VHF Antenna Using a Diplexer
A diplexer looks like a coax cable splitter, however, it is designed to combine a UHF antenna and a VHF antenna into one coax cable. During the year 2009, The Federal Communications Commission (FCC) moved almost all TV stations to UHF. This was done to free up the airwaves for cellphones and other wireless devices. There are a handful of stations that broadcast in VHF. Almost every major city has at least one TV station broadcasting in VHF while all the others are broadcasting in UHF. As a result, there are an overwhelming number of UHF only antennas on the market. If you have a UHF only antenna, you can buy an antenna that receives VHF and combine it to your UHF only antenna by using a diplexer. No multi-path interference will occur.
A combination antenna receives both UHF and VHF signals. If you connect two combination antennas into a diplexer, the diplexer will use one antenna for VHF only and the other antenna as UHF only. The UHF signals from the one antenna is combined with the VHF signals from the other antenna and placed into one coax cable. This prevents any multi-path from occurring.
