Study on Design Method of Antennas Used for Mobile Telecommunications

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1. A simple and efficient method which make use of the Green's function in the interior region of conducting scatterer has been proposed. This method has been applied to analyses of two-dimensional magnetic source located on a conducting rectangular cylinder and a three-dimensional slot antenna located on a conducting box which is the typical built-in antenna used for portable telephone. For the two-dimensional case, the accurate results have been obtained by introducing the method of least square even when arbitrary sources are assumed in the interior region. In the three-dimensional problem, the accurate results have been again obtained and the great advantages such as a simple procedure and a short run time of the computer have been confirmed.2. The conventional Galerkin-moment method analysis has also been carried out and the results have been compared with those by the new method. Although the method of least square has been used, the run time of the computer for the new method is about one tenth of that for the conventional Galerkin-moment method. Thus, the advantage of the new method has been confirmed.3. In order to improve the method 1 mentioned above, variational principle has been introduced. The results show that the accuracy is improved and the run time of the computer is greatly reduced (about one tenth of that of the method 1). Thus, this method is considered to be useful for an efficient design method of antennas for portable telephone. However, spurious resonances have been also observed and a further investigation is necessary to overcome this problem.4. A built-in antenna (S-shaped antenna) for the portable telephone has been experimentally developed. A very small (8cc) antenna has been obtained for portable telephone at 800MHz.