Directivity and SLL optimization of time modulated concentric circular antenna array synthesis: an hybrid evolutionary approach

Abstract

In this paper time modulated concentric circular antenna array (TMCCAA) with isotropic elements has been considered for the reduction of side lobe level (SLL) and improvement of Directivity by a hybridized method based on gravitational search algorithm with differential evolution (GSADE). The great difficulty while designing of optimal pattern synthesis is that simultaneous reduction of SLL and Directivity. This is the very challenging task for the antenna designer. To overcome these difficulties and challenges the authors have designed a novel unique cost function dealing with conflicting pattern characteristics like SLL reduction and Directivity improvement, modeled as a single objective optimization with suitable weighting factors for the objectives. Novel application of GSADE has been done in the field of pattern synthesis of TMCCAA. Investigation has been made regarding the effects of various control parameters for optimal pattern synthesis in TMCCAA with two case studies: Case-1 and Case-2. From the simulation results, it is clear that Case-2 outperforms Case-1 with respect to side lobe level (SLL) and Directivity. Apart from this the powers radiated at the centre/fundamental frequency, the first two sideband frequencies, and dynamic efficiency have been computed. It has been observed that as the sideband frequency increases, powers radiated by the harmonic frequencies and the sideband levels decrease. For statistical analysis, t test has also been done for the test of stability of GSADE over real coded genetic algorithm, conventional particle swarm optimization and differential evolution, and gravitational search algorithm for Case-2.