Detection of localised array fault from near field data

The technique of localized fault diagnosis in an array antenna system is considered. Commonly available software provides transformation of near zone measured data to the far field pattern in the visible region only. It is shown that the reverse transformation of this far.field pattern in the visible region back to the aperture fails to detect the localized fault. However, in the case of the forward transform, if the far field pattern is computed not only in the visible region but also well into the invisible region, the detection of the localized fault is found to be possible by doing the reverse transformation of these data, which extends well into the invisible region. Since a commonly occurring fault in a passive array is the phase-only fault, the concept has been validated by a simulated example of this type of fault.<>