In satellite TV installation, using diplexers is almost always recommended to eliminate unnecessary cost of wiring, labor and installation materials necessary to run two coaxial drops: one coming from the satellite dish and the other from the Over-The-Air antenna for local channels. Why have two coaxial cables traveling the length of your home when you can have just one.

a sonora satellite TV diplexer

What are satellite TV diplexers?

Satellite TV diplexers are passive devices whose main function is multiplexing signals with differing frequency domains into one channel. A typical diplexer will have three ports: a lowpass filter port and highpass filter port both connecting to a third port. Since the signals are occupying different frequencies, both these signals can coexist on a single communications channel without interfering with each other.

In the broadest sense, diplexers are used in satellite TV installation to allow the signal of your satellite TV programming and the signal of your Over-The-Air antenna which you use for your local channels to share a single coaxial cable, instead of having one coaxial cable for each device.

The advantages are obvious: first, it significantly reduces the number of cables running all over your home and makes the overall wiring architecture simple, and two: it makes troubleshooting (and expansion later on) a lot easier.

Satellite TV Wiring with a Diplexer

With a diplexer, you will need only one coaxial cable for both your satellite TV programming and local station programming. Here’s an example:

Since diplexers are reciprocal: meaning these devices doesn't have a notion of input or output, you can feed a signal right back down the same coaxial cable. Here’s an example showing how you can feed a processed signal right back down the line which you can then split to feed a second, third or fourth television set, courtesy of ProSatellite Supply: