Design of a multiband CPW-fed monopole antenna using a particle swarm optimization approach

A novel coplanar waveguide fed planar monopole antenna for multiband operation is presented in this paper. By embedding appropriate slits into the 50 Ω feeding line, good impedance matching for multiresonant mode is obtained. The evolutionary design process of using a particle swarm optimization (PSO) algorithm in conjunction with the method of moments is employed to effectively obtain the geometry parameters of the antenna for optimum multiband performance. Prototypes of the obtained optimized design have been constructed and experimentally studied. The measured results explore good multiband operation with 10 dB impedance bandwidths of 55%, 8.5%, and 4.4% at bands of 2.51, 3.98, and 5.24 GHz, respectively, which cover the personal communication system and 2.4/5.2 GHz wireless local-area network operating bands, and show good agreement with the numerical prediction. Good monopole-like radiation patterns and antenna gains over the operating bands have also been observed. Effects of the patch size on the antenna performance and implementation of the physical PSO for the optimized configuration are all examined and discussed in detail.