0-dB gain antennas radiate more energy higher in the vertical plane to reach radio communication sites that are located in higher places. Therefore, they are more useful in mountainous and metropolitan areas with tall buildings. A 2dB or 3dB gain antenna is the compromise in suburban and general settings. A 5dB gain antenna radiates more energy toward the horizon (compared to the 0, 2, and 3dB antennas) to reach radio communication sites that are further apart and less obstructed. Therefore, they are best used in flatlands and open areas.