Multi-Antenna system for a handy phone to reduce influence by user's hand

Abstract

A multi-antenna system without any switching circuits, which is suitable for the CDMA handy phone is proposed. The proposed antenna system is composed of the two quarter wavelength monopole antennas (QMPA) located at the top and bottom of the handy phone, and the two QMPAs are simultaneously fed through a power divider in phase and same amplitude. The radiation efficiency is measured in three conditions that upper, center and lower portions of the handy phone are held by user's hand in the talk position. The radiation efficiency is generally high in the all conditions even if one of the QMPAs is wrapped by the hand. The proposed antenna system is effective to reduce the influence by user' hand. Moreover, the phase difference in feed circuit is varied by inserting a phase sifter between the power divider and the QMPA. As a result, slight variation of the radiation pattern radiated from the two QMPAs is not effective for further improvement of radiation efficiency in the talk position.