Optimization of Five-Element Nu-Dipole Yagi-Uda Antenna Using Genetic Algorithms

Abstract

The paper analyzes the radiation characteristics of an optimized five-element Nu-dipole Yagi-Uda antenna array. Integro-differential equation for the antenna array was formulated. Method of Moment (MOM) technique was then used to convert the formulated integro-differential equation into a matrix form in order to obtain current distribution on the array. Upon computing the current distribution on the antenna array, maximum directive gain, input impedance(Zin) and far zone electric field (Eq(, = 90°)) were obtained for uniformly perturbed directors’ element lengths and spacings. A combination of MOM and Genetic Algorithm (GA) was used to maximize directive gain as a single objective function for the five-element array. Directive gain and input impedance of 12.31 (dB) and Zin= 4.46 + j 27.0 () and 11.71 (dB) and Zin = 2.41 – j 2.70 () were obtained for Micro-GA and Conventional-GA, respectively. These results were better when compared to 11.00 (dB) and Z in= 2.94 + j 7.20 () for the uniform perturbation. Composite objective function comprising directive gain and input impedance produced values of 9.58 (dB) and Zin= 75.80 – j 0.60 () for Micro-GA and 9.60 (dB) and Zin= 75.48 + j 5.35 () for Conventional-GA, respectively.