There are 2 major types of antennas used in WiFi Extenders:
Omni Directional Antenna: These antennas are used for or sending/receiving a signal in all directions (360 degrees). The benefit of these antennas is that they do not have to be aimed at the source of your signal (Access Point). If you travel a lot, this is the type of antenna that takes the least amount of effort when setting up, you do not have to locate the AP and aim the antenna toward it. Most of these WiFi Extenders have a connector for either antennas or antenna cables for remotely mounting the antennas.
Directional Antenna: Some of the WiFi Extender products incorporate the antenna inside the WiFi Extender’s case and are mostly Directional antennas and need to be aimed at the CG’s Access Point. They usually have a signal range of about 70 degrees, so they need to be aimed at the Access Point. They also make external mounted Directional antennas.