A graph showing the variation in sensitivity of a radio antenna with direction, which is also generally the same as the pattern of energy radiated by the same antenna when used as a transmitter (see antenna pattern). For many antennas, the pattern will vary in three dimensions, so that two polar diagrams at right angles are needed to show the complete variation. Polar diagrams for arrays of antennas usually show a main lobe, along the centre of which the sensitivity is highest, but also side lobes which show that the antenna will detect some sources at large angles from its central axis.