A Balance-Fed Loop Antenna System for Handset

Hisashi MORISHITA  Hiroki FURUUCHI  Harushige IDE  Zengo TANAKA  Kyohei FUJIMOTO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E82-A   No.7   pp.1138-1143
Publication Date: 1999/07/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Multi-dimensional Mobile Information Networks)
antenna,  handset,  balanced feed,  loop configuration,  current distribution,  

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In the conventional antenna system for the handset, some gain degradation has been observed when an operator holds the handset. This is caused by the variation of the current on the conducting box used in the handset due to the body effect. This paper presents (1) design concept of antenna for the handset and (2) analysis of a newly proposed loop antenna system, which has the balance structure for the antenna feed to reduce the effect of currents on the conducting box. In order to confirm the effectiveness of using the balance-fed loop antenna, a simple model using a small loop antenna mounted on a ground plane is analyzed. The current distribution for the balance-fed loop antenna system is obtained calculatedly and also experimentally and is compared with that for the unbalance-fed loop antenna system. In a result, remarkable decrease in the current distribution on the ground plane for the case of the balance-fed antennas system is shown. Calculated results are in good agreement with measured results.