QPSO for synthesis of linear array of isotropic antennas to generate flat-top beam including multiple null placement

The authors proposed an evolutionary algorithm based on quantum particle swarm optimization to generate flattop beam from a linear array of isotropic antennas. An effort is also made to reduce the side lobe level including multiple null placements with minimum variation in ripple of flat-top beam. This is generally done by changing excitation current amplitude of the elements. Phases of some of the elements are kept either at zero degree or at 180 degree. The generated pattern is broadside in the vertical plane. One example has been presented with twenty-six isotropic antennas. Array factor is calculated by using inverse fast Fourier transform to reduce the computational time significantly. The results obtained from the given example demonstrate the effectiveness of the proposed method. Although, the proposed method is developed and applied to a linear array of isotropic antennas; however, the principle can easily be extended to other type of arrays.