dBm
Relative way to indicate an absolute power level in the linear Watt scale
1 mW = 0 dBm
Isotropic radiator
Theoretically perfect sphere that radiates energy equally in all directions
Not possible to build a real isotropic radiator since it needs a power source or signal cable connected to it at some point on the surface.
Provides a reference point for representing the gain of an antenna
A unit for the antenna gain compared to an isotropic radiator gain
Usually expressed in dB isotropic (dBi)