For lateral guidance, known as the localizer, the antenna is normally placed centrally at the far end of the runway and consists of multiple antennas in an array normally about the same width of the runway. Each individual antenna has a particular phase shift and power level applied only to the SBO signal such that the resulting signal is retarded 90 degrees on the left side of the runway and advanced 90 degrees on the right. Additionally, the 150 Hz signal is inverted on one side of the pattern, another 180 degree shift.