Research on Desighn Method of Antennas Used for Compact Portable Telephine

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In order to establish design methods of antennas used for the portable telephones, analyzes of the characteristics of antennas mounted on a conducting body of the portable telephone have been performed using a new method proposed by the present investigators, the Galerkin moment method and the finite diffierence time domain (FDTD) method. S-shaped antenna, which was developed by the present investigators, has been designed by the FDTD method and fabricated.1. The new method, combining the interior Green's function of the conducting box and the moment method has been applied to the analysis of the antennas mounted on the conducting box. The results show that the accuracy of the analysis is almost the same to that of the conventional Galerkin moment method, while the required CPU time is about 1% of that in the moment method. Numerical results of the characteristics of a slot antenna and a monopole antenna mounted on the conducting box have been obtained . Thus, it has been confirmed tha … More t the new method is available for the numerical design method of the portable telephone antennas. The present method has been applied to analyze the characteristics of a slot antenna on a conducting circular cylinder with finite length.2. The characteristics of typical antennas used for the portable telephone such as the monopole antenna, the planar inverted F-shaped antenna and the S-shaped antenna have been and analyzed by using the FDTD method, the validity of the FDTD method for the design method of the portable telephone has been confirmed. The effect of a dielectric layr surrounding the body of telephone and the influence of the human body have been also analyzed and discussed.3. S-shaped antenna has been numerically designed by the FDTD method and fabricated. It has been shown experimentally that the S-shaped antenna has a wide frequency band width even when the volume of the portable telephone is less than 100cm^2 and the decrease of the radiation efficiency in the presence of the human body is small. Less