On array failure mitigation using genetic algorithms and a priori joint optimization

Antenna arrays are widely used in communications systems, especially in base-station installations, mainly for improvement of system capacity and spectral efficiency. The possibility of an antenna-array element failure is examined in this paper. If an element fails during operation, a significant degradation in the array´s performance is observed, even after the redistribution of the excitation coefficients of the remaining elements. In recent research in the field, the redistribution of the elements´ excitation coefficients is performed after the array failure, and the possibility of failure is not taken into account during the design of the array. In this paper, the possibility of a one-element failure is predicted and properly treated in early design stages. If the array is initially designed taking into account the possibility of a one-element failure, the elements´ coefficients are redistributed more efficiently and the failure mitigation is superior. In order to demonstrate the applicability of the proposed technique, two eight-element, switched-beam circular arrays, covering the horizontal plane, were designed using the method of genetic algorithms (GAs). The array elements were considered to be identical dipoles, placed vertically to the x-y plane. The beamwidth of the main-beam lobe was 45° (2π/N where N is the number of the array elements), the while maximum relative side lobe level (RSLL) was intended. Numerical results showed excellent agreement with the design goals.