___ transmission systems transmit tightly focused beams of radio signals from one ground-based microwave transmission antenna to another.

Terrestrial microwave

Explanation:

Based on the information provided it can be said that the type of transmission system being described is called a Terrestrial microwave transmission systems. This is a system used between ground-based microwave transmission antennas which produce a narrow, highly directional signal to another antenna in order to communicate information back and forth. Although very effective, it limits the communication to only the antenna's that have a line-of-sight with each other.

answer; i believe the correct answer is : communicate safe work practices;