Microsoft Word - Optimal Design of a Compact filter for UWB applications Using an Improved Particle Swarm Optimization_final_3

This paper shows an improved particle swarm optimization (PSO) to design a novel compact ultra wideband (UWB) filter. The filter consists of an only one-cell composite right and left handed-transmission line (CRLH-TL) resonator, stepped impedance (SI), and two spurlines. The one-cell CRLH-TL resonator has a compact size and forms a wide passband. An SI and two spurlines are employed to reject both the harmonics out of the UWB and the wireless local area network (WLAN, 5.15-5.825GHz) band. In order to optimize efficiently the filter, the design of the proposed filter is performed by an improved PSO which takes a suppression of the ripple effect in the passband. During the proposed procedure, the objective function converges only after 96th iteration, while the characteristic of the filter is optimized in acceptable results. The proposed filter has the overall size of 14 x 15mm2(0.63λg x 0.53λg), a bandwidth of 105% for a return loss > 10 dB, an insertion loss < 0.98dB, and stopbands at 11.5~22GHz and WLAN band. Moreover, the ripple in the passband is minimized by the improved PSO.