Patent ID: 7804459

Claim:
A dual-band monopole antenna comprising: a monopole antenna having a signal feeding terminal and a load connection terminal; and a transmission line load comprising: a core transmission line having an antenna connection terminal and a short-circuit terminal, the antenna connection terminal being in connection with the load connection terminal of the monopole antenna; an outer circumferential conductor circumferentially surrounding and spaced from the core transmission line, the outer circumferential conductor having an open terminal and a short-circuit terminal opposite to the open terminal, the short-circuit terminal being connected to the short-circuit terminal of the core transmission line, so that the outer circumferential conductor forms an open structure facing the monopole antenna; and a short-circuit section extended from the short-circuit terminal of the core transmission line to provide the short-circuit terminal of the core transmission line with a short-circuiting structure; wherein a length from the short-circuit terminal of the core transmission line to the open terminal of the outer circumferential conductor forms a short-circuit transmission line length, the short-circuit transmission line length corresponding to an equivalent quarter of a wavelength of a predetermined second resonant frequency, a combined overall length of the monopole antenna and the transmission line load being set corresponding to an equivalent quarter of a wavelength of a predetermined first resonant frequency, such that the first resonant frequency is determined by a length of the short-circuit section that is connected to the short-circuit terminal of the core transmission line.