Two novel antenna designs for mobile handsets are proposed in this thesis. With a helix loading, an inverted-L monopole antenna capable of generating two resonances at about 900 and 1850 MHz is first presented. The operating bandwidths obtained cover the required bandwidths of the GSM/DCS/PCS bands. Besides, an internal mobile handset antenna comprising a PIFA and a PILA, which are, respectively, designed for covering the GSM and DCS/PCS bands is also presented. The PIFA and PILA together occupy a compact volume of 7.2 ¡Ñ 20 ¡Ñ 40 mm3, and are suitable to be built-in within the housing of a mobile handset.