A low-profile planar monopole antenna for multiband operation of mobile handsets

A novel planar monopole antenna with a very low profile (antenna height less than 0.04 times the operating wavelength in the free space) and capable of multiband operation is proposed. The proposed antenna has a planar rectangular radiating patch in which a folded slit is inserted at the patch's bottom edge. The folded slit separates the rectangular patch into two subpatches, one smaller inner subpatch encircled by the larger outer one. The proposed antenna is then operated with the inner subpatch resonating as it quarter-wavelength structure and the outer one resonating as both a quarter-wavelength and,a half-wavelength structure. The proposed antenna, 12 mm in height and 30 mm in width has been constructed, and the obtained bandwidths cover the global system for mobile communication (890-960 MHz), digital communication system (1710-1880 MHz), personal communication system (1850-1990 MHz), and universal mobile telecommunication system (1920-2170 MHz) bands. Details of the proposed design and obtained experimental results are presented and discussed.