Abstract: A multi-band planar inverted-F antenna includes a radiating unit, a ground unit and a feeding unit. The radiating unit includes a common radiating element, a high-frequency (HF) radiating element and a low-frequency (LF) radiating element. A quasi U-shaped slot is defined between the HF radiating element and the LF radiating element. The ground unit is electrically connected to one side of the common radiating element. The feeding unit includes a strip electrically connected to one side of the HF radiating element. The ground unit includes a ground point and an inverted-L short-line connected to the ground point at one end thereof. The inverted-L short-line is also electrically connected to the common radiating element at another end thereof. A loop surface current induced by the inverted-L short-line can advantageously enhance bandwidth of the multi-band planar inverted-F antenna at frequencies of interest.