FOLDED LOOP ANTENNA FOR MIMO APPLICATION IN MOBILE PHONES

Abstract

Recent developments in wireless communications have shown that by using multiple antenna elements at both transmitter and the receiver, it is possible to substantially increase the capacity in a wireless communication system without increasing the transmission power and bandwidth. This system with multiple antenna elements at both link-ends is termed the MIMO (Multiple-Input Multiple-Output) system. Despite considerable research being done on MIMO systems, the design of realistic diversity antennas on mobile terminals for MIMO systems remains a challenging issue. The main challenge in designing two or more antennas on a small mobile terminal is to achieve a high isolation between the antennas. It is very difficult to achieve a high isolation with the existing handset antennas, such as PIFA (Planar Inverted-F Antenna), which induce substantial surface currents on the ground plane. In this dissertation, a compact self-balanced antenna which is a folded loop antenna is proposed to challenge antenna design. Based on the proposed compact self-balanced antenna, a two element array is designed (using IE3D Simulator) and tested for various orientations on small ground plane for mobile phone. A correlation of less than 0.1 was observed between the two antennas. Characterization of MIMO array ' was done on the basis of parameters: correlation coefficient, mutual coupling, current distribution and Total Active Reflection Coefficient.