Polarisation is perhaps the most fundamental characteristic of an antenna which describes the plane in which its electric field radiates.
External antennas found under this section are classed as Passive Antennas. These types of antennas connect to a device such as a modem, repeater, or wireless radio using coaxial cables.
Passive antennas have been up until recently been the most common type of external antenna for 3G and 4G technologies, and some low frequency wireless technologies. They are typically simple in construction and support frequencies up to around 3 GHz and multi antenna up to 2x2 MIMO.