Side lobe level suppression in a thinned linear antenna array using particle swarm optimization

This paper presents thinning of a linear array that generates radiation patterns with reduced peak side lobe level (PSLL). Uniform amplitude excitation across all the elements is assumed and particle swarm optimization (PSO) technique is used to estimate the optimum combination of ‘on’ and ‘off’ elements corresponding to lowest possible peak SLL. In order to assess and validate the performance of proposed method for thinning of a linear conventional array, an array consisting of 100 sources with a cos0 element pattern and uniform inter-element spacing of 0.5X is considered. Array performance is compared with the results obtained for the arrays in which all the elements are turned ‘on’ and with those of previously published results. The capability of proposed method is further demonstrated for thinning of linear phased array by assuming the array of 100 isotropic elements which is steered to 60° with respect to antenna boresight. The radiation pattern characteristics of the phased array for the specified scan angle is reported and compared with those obtained at antenna boresight.

I. Introduction

Various radiation characteristics of an antenna array such as side lobe level (SLL), half power beam width, directivity and gain can be controlled and optimized by adjusting some of the basic array parameters, which include total number of antenna elements, the spacing between them, their amplitude excitation coefficients and relative phases along with the geometrical configuration of overall array like linear, planar, circular, elliptical etc. [1].