Patent ID: 7804457

Claim:
A multi-band antenna, adapted to operate in a first frequency band and a second frequency band which is lower than the first frequency band, the multi-band antenna comprising: an antenna element comprising; a first end, adapted to be electrically connected to a power feeding point; and a second end; and a circuit, electrically connected between the second end of the antenna element and a ground in a serial manner, wherein: the antenna element is configured to serve as an antenna only in the first frequency when the second end is not electrically connected to the circuit, and the antenna element is configured to serve as an antenna in both the first and the second frequencies when the second end is electrically grounded through the circuit, wherein: the antenna element has an electrical length of ¾ wavelength of the first frequency band; the circuit includes an inductor; and the inductor has such an inductance that an electrical length of the antenna element and the inductor corresponds to ½ wavelength of the second frequency band.