Summary
International Symposium on Antennas and Propagation
2010
Session Number:3TA1
Session:
Number:3TA1-4
Electrically Small Antenna for a Handy Terminal
Tan Watanabe, Marie Tsurunaga, Yasushi Hamada, Takahiro Inada, Naobumi Michishita, Yoshihide Yamada,
pp.-
Publication Date:2010/11/23
Online ISSN:2188-5079
Summary:
Recently, the remote keyless entry system is conveniently employed in private cars [1]. In the future system, expanding the communication range of a handy terminal is requested. This system uses the 315MHz band. Therefore, the handy terminal antenna must be achieved in a very small size less than 0.05 wavelengths. On the other hand, high antenna gain is requested in the handy use for the long communication distance. For these purposes, a normal-mode helical antenna (NMHA) is thought suitable. High antenna gains of NMHA were ensured in the case of metal plate proximity [2],[3]. However, effects of human hand were not clarified. In this paper, first of all, design methods of a NMHA for efficient radiations are clarified. In a very small antenna, because the input resistance is very small less than a few ohms, antenna impedance matching to a feed cable becomes very important. Therefore, an impedance matching method by the off-set feed configuration is clarified. In order to ensure the design adequateness, calculated results are compared with measured results. Finally, affects of a human hand to the designed antenna are investigated in electrical characteristics such as input impedances and radiation patterns.