A folded loop antenna system for handsets developed and based on the advanced design concept

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 ante nna performance due to the body effect, and (3) of reducing SAR value in th e human head at the handset talk position, in addition to the indispensable requirements for handset antennas such as (4) low profile, and (5) light w eight. The technology applied is to make this antenna (a) an integrated str ucture, which is a typical application of the fundamental concept of making antennas small and (b) a balanced structure which has been proved to be ve ry effective to satisfy the requirements (2) and (3). The antenna is essent ially 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-wavele ngth. It does not have really a balanced structure, as is fed with an unbal anced line; however, the antenna structure itself can eliminate the unbalan ced current flow on the feed line as in the balanced antenna system. Both t heoretical and experimental analyses have been shown and the usefulness of the antenna is discussed. This paper may suggest the advanced technology an d design concept that will be applied to the development of handset antenna s toward the future.