Antennas

Antennas or aerials are used to transmit or receive radio signals. Devices that perform both transmission and receiving of signals are known as transceivers.

Antennas that radiate in all directions are known as isotropic antennas. This is an ideal case that doesn't really exist.

Gain

The gain of an antenna tells you it's degree of diagonality. Gain is measured in decibels relative to isotropic (dBi). An isotropic antenna has a gain of 0dBi, and antennas with a higher gain are more directional.

Some manufacturers also measure gain in decibels relative to dipole (dBd), which is relative to the dipole antenna.

0 dBd = 2.15 dBi