: is the relative measurement of an antenna’s ability to direct or concentrate the radiated signal emitting from it. Gain is measured in Dbi (decibels relative to an isotropic radiator) or Dbd (decibels relative to a dipole radiator). Isotropic radiator
: is a theoretical single point in space that radiates energy equally in every direction similar to the Sun radiating its light. The isotropic radiator exhibits the same magnitude or properties when measured in all directions. It has no preferred direction of radiation. It radiates uniformly in all directions over a sphere centered on the source. Decibels
: a unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale. A change in power by a factor of 10 is a 10 dB change in level. for every 3db increase on the scale, its power is doubled.