A splitter is an accessory that allows for additional inside antennas.
Typically, a splitter is used to take one cable run and split it into two, three, even up to four cable runs, which means one line is able to do 4 inside antennas.
However, this also means that the signal strength is also being split across the cable runs and antennas. So it's highly dependent on having enough boosted signal to make sure there's enough broadcasting range for all additional inside antennas.
Learn more: www.wilsonamplifiers.com/splitters-taps/