Adaptive Differential Evolution Algorithm to Design Broad-Band Array with Fixed Side Lobe Level and Optimum Voltage Standing Wave Ratio

This paper investigates the application of Adaptive Differential Evolution (DE) algorithm to enhance the performance of broadband antenna. A linear array consisting of half wavelength long unequally spaced parallel dipoles is designed to meet the increasing demand of extremely large bandwidth in wireless communication systems. Array is devised to maintain an almost invariable radiation patterns over a wide range of frequencies. Constant beam widths, good side lobe characteristics and minimum bearable voltage standing wave ratio (VSWR) are achieved for the allocated frequency band. Coupling effect has been taken into account via induced EMF method and minimized in terms of VSWR. In the proposed technique excitation and position of the individual array element are optimized in order to obtain a fixed SLL and minimum bearable VSWR over the proposed bandwidth. Dynamic range ratio (DRR) of excitation distribution is fixed at an optimum value for further mitigation of coupling effect. Phase distribution for all the elements is kept at zero degree. An adaption schemes to tune the scaling factor and crossover rate of population in DE is used to solve the design problem. Numerical results show the aforementioned modifications make the algorithm more effective to design the proposed broadband array.