Guide to Splitters and Combiners

Guide to Splitters and Combiners  main image Guide to Splitters and Combiners  image

What is a Splitter?

A, 'X'-way signal splitter is a small RF component that sits inline (in between the antenna and device), with one input and 'X' outputs.

For a 2-way splitter, the input signal is split equally into two output signals, each reduced by 3dB (i.e. halved), due to the 1:2 power division.

A small signal loss is incurred, as no electrical device can ever operate at 100% efficiency.

When determining whether you can afford to split your signal you must consider if your signal is strong enough to be halved between each device.

In very low signal areas, it's often advisable to use two antennas instead of a splitter.

Signal will always be divided regardless of whether two devices are actually connected to the splitter.


Theoretical Insertion Loss

No. of Output Ports Insertion Loss (dB)
2 3.0
3 4.8
4 6.0
5 7.0
6 7.8
8 9.0

Output Power = 1/Ports


What is a Combiner?

Flip the splitter upside-down and you've got a signal combiner.

In this sort of setup, you're aiming to combine two (or more) inputs into one output, most commonly observed when phasing antennas.

While it is possible to sum two input signals with no loss, this can only be accomplished if the input signals are identical in phase and amplitude.

When two signals are completely out of phase (180 degrees) the signals will cancel completely, hence the statistical average for two unknown signals is a 3dB combination loss (i.e. reduced by half).

Because a second antenna can only ever give a maximum of a 3dB power increase, it's important to phase the antennas correctly.