Novel MIMO antennas for mobile terminal

Radiation from a small device is dominated by the chassis, not only by the antenna structure attached to it. We propose a MIMO antenna system considering the mobile phone chassis as the main radiator. Since the chassis supports multiple orthogonal mode currents at a certain frequency, we couple to four of these modes using four miniature capacitive couplers to realize a four port antenna system. Although impedance characteristics of different modes are inherently different, matching at the system ports is sufficient to use this MIMO antenna system for 2.4 GHz ISM band.