Patent ID: 8614647

Claim:
An antenna device comprising: a folded monopole antenna comprising a forward portion and a backward portion, with an end of the forward portion being connected to a feeding point and an end of the backward portion being connected to a ground point via a first lumped parameter circuit; a stub provided between the forward portion and the backward portion and configured to shunt the forward portion and the backward portion; and a conductor in parallel to the first lumped parameter circuit and comprising a first end and a second end, with the first end being connected between the stub and the ground point, and the second end being open; wherein an electrical length from the feeding point to the ground point via the folded monopole antenna is equal to or near ½ a wavelength of a first resonant frequency, and an electrical length from the feeding point to the second end of the conductor via the forward portion, the stub, and the backward portion is equal to or near an integer multiple of ¼ a wavelength of a second resonant frequency.