Improved compact low-profile quadband planar monopole antenna for mobile handsets

A compact internal planar monopole antenna capable of multiband operation of mobile handsets is presented. The antenna has a very low profile and covers GSM900, DCS1800, PCS1900 and UMTS2050 bands. The two operating modes of the proposed antenna are associated with various length of two monopoles, in which the shorter monopole is resonating as a quarter-wavelength structure and the longer one resonating as both a quarter-wavelength and a half-wavelength structure. The radiator of the proposed antenna is embedded in dielectric medium to improve its characteristics.