Input Impedance-Tuning Slots of PIFA Antennas

Input impedance-tuning methods are proposed for antenna designs of mobile communications devices. The proposed method can be applied to input impedance-tuning of single- band, dual-band and multi-band PIFA (planar inverted-F antenna) antennas. The prominent feature of this impedance-tuning method is to use an inductive-tuning slot or a capacitive-tuning slot, rather than the width of the grounding and feeding strips and/or the gap between the grounding and feeding strips, to get desirable impedance matching and bandwidth.