Radio waves travel in straight lines. Two-way radios operate with line of sight communication. When one two-way radio is in the direct line of sight of another, communication is clear and unbroken.

Radio waves can navigate through some obstructions, but this will impact the strength (range) and clarity of communication. This is a problem in areas with mountains and a lot of hills. Also, on flatter terrain, just the distance between the two radios can drastically weaken the radio range.

Repeaters act as a combination of a radio receiver and radio transmitter. They receive a signal and transmit it so that two-way radios can cover longer distances and navigate obstructions. This makes repeaters the middle man between two repeater-capable radios.

The higher you mount the antenna, the better coverage you can get. Thus, repeaters are typically installed high up on a building or hill in a centrally located area. The better the spot of repeater installation, the better the radio range.

A repeater won't just push radio range further, but it'll also improve the clarity of two-way radio transmission.