Analysis and Recovery Optimization of Sporadic Reflectarray Phase Failures Based on Array Factors

In a given antenna array system, it is not uncommon for failures affecting either the phase or amplitude of the individual elements to occur. Much work has investigated the effect and mitigation of fabrication or tolerancing errors on the main beam gain and sidelobe level from a statistical perspective. However, there are few discussions elaborating upon similar effects for the case of more sporadic random errors likely to occur throughout the operational lifetime of an array. Further, the more recent, prominent use and application of reflectarrays merits beginning to extend these failure analysis concepts to cover such antenna systems. In this work, it is shown that a 20 x 20 element reflectarray possessing a unit cell phase range of 300 degrees can sustain a failure rate of 25% and still remain above the 3 dB loss threshold when steered to broadside. For the case of 25% failure, it is possible to recover approximately 1 dB of the mainbeam gain for losses greater than 2 dB. Additionally, in the case of more structured full-column failures, the performance begins to drop below 3 dB down in the worst case at 15% failure. Similar to individual unit cell failures, it is possible to retune the remaining working elements to regain over 1 dB of lost gain.