A Folded Loop Antenna System for Handsets Developed and Based on the Advanced Design Concept

Yongho KIM  Hisashi MORISHITA  Yoshio KOYANAGI  Kyohei FUJIMOTO  

IEICE TRANSACTIONS on Communications   Vol.E84-B   No.9   pp.2468-2475
Publication Date: 2001/09/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Innovation in Antennas and Propagation for Expanding Radio Systems)
Category: Mobile Antennas
small antenna,  handset,  design concept,  balanced system,  body effect,  

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Analysis of a novel folded loop antenna for handset is described along with the advanced design concept for handset antennas. The design concept shown in this paper meets the foremost requirement for handset antennas such as (1) small size and yet (2) has capability of mitigating degradation of antenna performance due to the body effect, and (3) of reducing SAR value in the human head at the handset talk position, in addition to the indispensable requirements for handset antennas such as (4) low profile, and (5) light weight. The technology applied is to make this antenna (a) an integrated structure, which is a typical application of the fundamental concept of making antennas small and (b) a balanced structure which has been proved to be very effective to satisfy the requirements (2) and (3). The antenna is essentially a two-wire transmission line, folded at about a quarter-wavelength to form a half-wave folded dipole, and yet appears to be a loop of one-wavelength. It does not have really a balanced structure, as is fed with an unbalanced line; however, the antenna structure itself can eliminate the unbalanced current flow on the feed line as in the balanced antenna system. Both theoretical and experimental analyses have been shown and the usefulness of the antenna is discussed. This paper may suggest the advanced technology and design concept that will be applied to the development of handset antennas toward the future.