Metamaterial ground plane is introduced to planar inverted-F antenna (PIFA) design to explore the potential improvement in radiation.Through replacing the conventional capacitance by a metamaterial resonance circuit,the modified PIFA transmission line model physically interprets its novel properties.As is shown,such metamaterial PIFA exhibits a -10 dB return loss for more than 100% of bandwidth with resonance covering all wireless local area network applications and broadband wireless access form 2 GHz to 6 GHz.Nearly omnidirectional radiation pattern is achieved at 2.4/2.5 GHz,but mainly backward radiation is obtained at 3.8 GHz and 5.1—5.8GHz.