What is a Splitter
A, 'X'-way signal splitter is a small RF component that sits inline (in between the antenna and devices), with one input and 'X' outputs. For a 2-way splitter, the input signal is equally split into two output signals, each reduced by 3dB (ie 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 that the signal will be halved between each device - is your signal strong enough? In very low signal areas it's often advisable to use two antennas instead of a splitter. Signal will be always be divided regardless of whether two devices are actually connected to the splitter.
Theoretical Insertion Loss
|No. of Output Ports||Insertion Loss (dB)|
Output Power = 1/Ports
What is a Combiner
Flip the splitter upside-down and you've got yourself 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 (ie 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.