Instrument landing system glidepath antenna array and drive therefor

摘要

An instrument landing system (ILS) glidepath antenna array and drive therefor which provides for lower susceptibility to above-ground interference and higher stability than the known M-array system. The antenna array also provides for a shorter image ground requirement than the known null reference and sideband reference systems. The antenna array comprises a four-element structure, two of which are driven with CBS only signals having relatively different amplitude and phase, and the other two elements of which are driven with SBO only signals having relatively different amplitude and phase.