When and how to split cell phone signal to achieve maximum strength ?

When it comes to designing a cell phone booster system for a large area 20,000 sq feet and above, sometimes adding an extra antenna can be determinant to the system. In a wide open space where there are no signal barriers like steel or brick walls a single indoor antenna would cover a wider area then two. The main factor that is going to decide the coverage you are going to attain depends on how strong a signal you have outside the building. The principle on which the cell phone booster works is that it takes a weak signal and amplifies into a better signal. The input signal determines how much amplification you can gain on the output. If the signal is mediocre meaning -65 dB to -85 dB, which translates to between 3-5 bars then the gain you can achieve with a 55dB amplifier is more then what you can gain with a 80dB amplifier with 1-2 bars at the input.

Now, when to split a signal and when not to split a signal to broadcast in two separate areas of a building. Every split results in some signal loss due to the action of splitting signal. And every 100 ft of cable run after the signal split results in approximately 6 dB loos of signal strength. Sometimes the losses incurred due to splitting and cable run will require to abandon the idea of splitting and installing a whole new signal booster system. Another important point to keep in mind is when to split the signal.
2-way-splitter

3-way-splitter

coupler

If one area of your building is larger then the other, then a couple can enable you to split signal more on one side then the other so the coverage on the building with larger area is more then the one on the smaller side.