Re-optimisation of linear and planar arrays with failed elements

Although one major advantage of array antennas is graceful degradation with element failures, if sufficient elements fail then performance will ultimately suffer. This manifests itself as loss of gain, increase in mean sidelobe level and increase in peak sidelobe. Some papers have appeared in the literature describing techniques for correcting for element failures in linear arrays but to our knowledge none has dealt with large planar arrays. This paper describes two techniques that have been explored for linear arrays and one which is particularly successful when applied to a large (2056 element) planar array. It is an extension of the technique described in a paper for linear array correction. The algorithms are well able to restore the desired mean sidelobe level and sometimes also to improve the peak level. However it is a fundamental consequence of lowering the sidelobes that a corresponding loss of gain occurs. By appropriate choice of parameters this can be kept to a minimum