DESIGN OF A QUAD-BAND INTERNAL FOLDED ANTENNA FOR MOBILE PHONES

Abstract

In this thesis, design of a quad-band internal folded antenna for mobile phones is presented. To understand planar inverted-F antenna (PIFA) technology at first, this thesis starts with history about mobile communication, basic theories about dipole and monopole antennas. After that, some important characteristics of PIFA and method to obtain wideband and miniaturizing technology are described. The theory of Specific Absorption Rate (SAR) is also discussed. To realize a quad-band internal folded antenna, the folded U-slit which is embedded in the radiating element, the additional bent strip and a narrow slit are used. The antenna is designed using HFSS based on Finite Element Method (FEM), MWS based on Finite Difference Time Domain (FDTD) and FEKO based on Moment of Method (MOM). To obtain the resonant mode for GSM900 operation, a quarter-wavelength folded U-slit is embedded in the radiating patch. Also, to create additional resonant modes for DCS1800, USPCS and DMB operations, a quarter-wavelength bent strip and a quarter-wavelength narrow slit are used in optimizing a quad-band internal folded antenna. Finally, the simulated 1.6g spatial-peak SAR values are obtained using SEMCAD X based on Finite Difference Time Domain (FDTD). The proposed antenna provides good return loss and radiation pattern characteristics in the frequency band of interest.