Self-balanced wideband folded loop antenna

Abstract

A folded loop antenna for handsets has already been introduced and shown as one of the balance-feed antennas for handsets, which is very effective at mitigating the antenna performance degradation owing to body effects. In order to meet the requirements for the latest handsets such as small size and wideband characteristics, a folded loop antenna is modified to have wider band characteristics. A folded loop antenna has a self-balanced structure so that the current on the ground plane (GP) can be reduced even though an antenna is fed by an unbalanced line such as coaxial cable. The antenna, which is introduced here, is also expected to maintain this effect. In the analysis, the electromagnetic simulator based on the method of moments (MoM) is used. Also design parameters, which are useful in practical operation, are found. An example of a wideband antenna, which has a self-balanced effect, is designed based on these parameters. In addition, antenna characteristics such as VSWR, the current distributions and the radiation patterns are shown. As a result, it has been confirmed that the antenna has wideband characteristics and a self-balanced effect.