Sidelobe level and nulls control of defected linear antenna arrays using an optimization algorithm

In the presented work, patterns are recovered (in terms of SLL, nulls positions and nulls depth) using PSO (particle swam optimization) algorithm on different size of linear arrays with random elements failure. 8 and 32 elements linear arrays are used with equidistance inter-element spacing of λ/2 at 10 GHz center frequency in X-band. The investigation is done only for broadside radiation patterns, and amplitude-only excitations are used for symmetrical nulls, while in asymmetric nulls, complex weights are required. The computed amplitudes/complex weights for sidelobe level (SLL) and nulls control with random elements failure are obtained using PSO through MATLAB coding. These PSO computed amplitudes/phases are then applied on designed microstrip patch antenna array at 10 GHz in CST Studio 2019. It is considered that the defected elements are not participating in the far field radiation, hence their excitation amplitudes/phases are set to zero in the CST setup. This work has three investigation cases, case 1: recovering SLL=-25 dB of defected arrays, case 2: recovering SLL=-25 dB with double symmetrical nulls at ±30° having null depth of -60 dB of defected arrays, and case 3: recovering SLL=-25 dB with double asymmetrical nulls at –30°, +60° dB having null depth of of -60 dB of defected arrays. Each case is performed on two different sizes of array: 1×8 and 1×32 linear arrays. In these three cases, 25% random elements are made defected and then the patterns are recovered using PSO. The original patterns (all elements are excited and contributing to radiation pattern), defected patterns (patterns with random 25% elements failure) and corrected patterns (patterns recovered using PSO) are compared and analyzed in MATLAB and CST simulators.