Design of a PIFA-Driven Compact Yagi-Type Pattern Diversity Antenna for Handheld Devices

This letter presents a compact folded-strip printed inverted-F antenna (FS-PIFA) having dipole-like radiation pattern. The designed antenna operates at 2.45-GHz band and offers 5.75% bandwidth. A parametric study of the FS-PIFA is presented to show the effect of symmetry on the quality factor. Next, an FS-PIFA-driven compact Yagi-Uda antenna is designed by using folded strips as passive elements. The dimension of the Yagi antenna is optimized using mutated particle swarm optimization (PSO) algorithm. The designed Yagi-Uda antenna operates in the 2.45-GHz band with front-to-back (F/B) ratio of 17 dB and gain of 4.6 dBi. Finally, a pattern diversity antenna is realized by placing two such Yagi-Uda antennas back to back with a common reflector. The diversity antenna is very compact, and it occupies approximately 41 ×68 ×5 mm
³
volume. The port isolation is about 24 dB. The signal envelope correlation coefficient of the diversity antenna is found to be as low as 0.074.