An efficient synthesis of unequally spaced antenna array with electronic scan capability utilizing particle swarm optimization

An efficient technique for synthesizing unequally spaced linear antenna (USLA) arrays is proposed for reducing the peak side lobe level (PSLL) while steering the main beam over the pre-specified scan angles. All the elements in antenna array are assumed to have constant amplitude and phase excitations and varying elements spacing within the range of 0.5λ - 1.5λ. Particle swarm optimization (PSO) algorithm is utilized to determine optimum combination of elements spacings corresponding to better design efficiency in terms of reduction in SLL not only at boresight but also at different scan angles. Unequally spaced arrays present a particular challenge of grating lobes because of average elements spacings greater than λ/2. In this study, authors attempted to overcome this limitation by appropriately determining the range of elements' spacing. A 16-element USLA array is chosen for optimisation and results obtained through the proposed method are verified against the uniformly spaced arrays at 300 and 450 scan angles.