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. There are right ways and wrong 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 image two different people talking to you at the same time. They are each reading a paragraph at the same speed. If each person is saying the same word at the same time, then you will understand them as they read the paragraph. If one person is slightly behind than the other person while both are talking, than it will be difficult understanding both persons at the same time. This is multi-path interference.

When two antennas are combined into one coax cable, they both "talk" to the TV tuner at the same time by delivering the TV signal. If both antennas do not consistently deliver the TV signal to the TV tuner at the exact same time, the TV tuner will not understand any of the signals from both antennas. As a result, multi-path interference occurs. There are a few ways to combine multiple TV antennas into one coax cable so multi-path interference doesn't occur.

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 [[1]] and sold by [Direct], the Johansson KIT7474L2 | Antennas Direct 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.) You CANNOT manually program the Johansson device, The Smartkom allows manual programming.

3. Combining Multiple TV Antennas Using a Diplexer

A diplexer looks like a coax cable splitter, however, it is designed to combine a UHF and 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 hook-up two combination antennas into a diplexer, the diplexer will use one antenna for VHF only and the other antenna as UHF only. The UHF signal from the one antenna is combine with the VHF signal from the other antenna and placed into one coax cable. This prevents any multi-path from occurring.

4. Combining Multiple TV Antennas Using a Splitter (NOT RECOMMENDED)

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: