You need to be able to identify different types of antenna systems for the following reasons:
Antenna selection— To select the best antenna for your particular application, you need to know what antenna types are available and what the characteristics are of each type.
Interference reduction— You will most likely deploy a wireless network in an area where one or more other wireless networks already exist. You need to be able to identify the antenna type, polarization, and coverage pattern that these existing networks are using. This information allows you to select antennas for your own network that will minimize interference from (and to) the existing networks.
The sections that follow describe the antenna types ...