A Uniplanar, Quasi-Isotropic Folded Dipole Design Based on Hybrid GA-PSO Optimization

A uniplanar quasi-isotropic folded dipole is proposed by using a hybrid genetic algorithm and particle swarm optimization (GA-PSO) algorithm. The proposed antenna is evolved from a half-wave dipole, where the dipole is folded to achieve a pair of out-of-phase line sources and an orthogonal line source, thereby obtaining a quasi-isotropic radiation pattern. Based on GA-PSO algorithm, the bending position is optimized for the minimum gain difference. For demonstration, the dipole prototype operating at 915 MHz is designed and fabricated in which a parallel transmission line with comb-like structure is adopted to achieve good impedance matching. The measured result shows a gain difference of 2.81 dB, and the simulated value is 0.34 dB. Compared with other quasi-isotropic antennas, the proposed antenna has merits of simple structure, low gain difference and uniplanar structure.