A multiband antenna comprising a ground plane and a radiating portion disposed on or above a dielectric substrate, wherein the radiating portion comprises: a first metal portion comprising a first coupling metal portion and a signal feeding line, wherein the signal feeding line is electrically connected to the first coupling metal portion and has a signal feeding point; a second metal portion comprising a second coupling metal portion and a shorting metal portion, wherein the shorting metal portion is electrically connected to the second coupling metal portion and has a shorting point electrically connected to the ground plane, and the second coupling metal portion is coupled to the first coupling metal portion and a capacitively-coupled portion is formed between the first and the second coupling metal portions (141,151); characterized by a localized inductively-coupled portion; and a third metal portion, wherein the localized inductively-coupled portion is connected between the third metal portion and the second metal portion, the localized inductively-coupled portion enabling the first and the second metal portions (14, 15) forming an open-loop metal portion which equivalently performs as another open-loop antenna to enable the multiband antenna to generate a first operating band, and wherein the open-loop metal portion equivalently performs as a feeding-matching portion of the third metal portion to enable the multiband antenna to generate a second operating band, wherein the frequencies of the second operating band are lower than those of the first operating band and the length of the third metal portion is less than or equal to one-fifth wavelength of the lowest operating frequency of the second operating band. a first metal portion comprising a first coupling metal portion and a signal feeding line, wherein the signal feeding line is electrically connected to the first coupling metal portion and has a signal feeding point; a second metal portion comprising a second coupling metal portion and a shorting metal portion, wherein the shorting metal portion is electrically connected to the second coupling metal portion and has a shorting point electrically connected to the ground plane, and the second coupling metal portion is coupled to the first coupling metal portion and a capacitively-coupled portion is formed between the first and the second coupling metal portions (141,151); a localized inductively-coupled portion; and a third metal portion, wherein the localized inductively-coupled portion is connected between the third metal portion and the second metal portion, the localized inductively-coupled portion enabling the first and the second metal portions (14, 15) forming an open-loop metal portion which equivalently performs as another open-loop antenna to enable the multiband antenna to generate a first operating band, and wherein the open-loop metal portion equivalently performs as a feeding-matching portion of the third metal portion to enable the multiband antenna to generate a second operating band, wherein the frequencies of the second operating band are lower than those of the first operating band and the length of the third metal portion is less than or equal to one-fifth wavelength of the lowest operating frequency of the second operating band.