| In wireless telecommunications, antennas play a very important role where they can either enhance or constrain system performance. The design characterization of such antennas is dependent upon, to large extent, the development of simulation tools that can accurately model general antenna system topologies. In this thesis, where the basic theory of finite-difference time domain method (FDTD) is reviewed, an FDTD code is developed for antenna design, with particular emphasis on the modeling of the source region. The results from the developed code are compared with those produced by a moment method based code ( Numerical Electromagnetic Code-2: NEC2) and very good agreement is obtained. The effects of the FDTD cell size and the distance between the outer absorbing boundary and the antenna on accuracy are explored. Some criteria for the choice of above parameters in FDTD calculation are given for antenna design. Using the developed code, a new planar monopole antenna which operates at dual wide band (800MHz band and 1800MHz band) is developed by cutting slots and determining the geometrical parameters. This dual frequency performance is required for the existing and potential mobile communication system providing analogue and digital services. |
