A SMALL 4 BY 4 MIMO ANTENNA SYSTEM FOR LTE SMARTPHONES

In this paper, we present a small 4 by 4 MIMO antenna system which occupies only two corners of the circuit board by locating two antennas in one corner together. The supporting frequency ranges are 3.4 to 3.6 GHz that is planned for MIMO service in Japan. The proposed antenna system consists of two pairs of antenna sets. Each of the antenna set consists of one inverted-F antenna and one coupling antenna. The coupling antenna has the property of the loop antenna, so it effectively isolates the induced current flow. We implement the prototype of our proposed antenna system and evaluate it via thorough experiments. Return losses are <-10 dB, isolations between antennas do not >-17 dB, ECCs are <0.03, gains in all ports are bigger than about -1 dB, and 3D radiation patterns are omnidirectional in all antennas. (C) 2016 Wiley Periodicals, Inc.