Theory of Characteristic modes application to MIMO Antennas

Authors: Dr. Asim Ghalib

Source: FERMAT, Volume 29, Communication 1, Sep.-Oct., 2018

Abstract: Fourth Generation (4G) and fifth Generation (5G) wireless communication devices rely on multiple-input-multiple-output (MIMO) technology to provide enhanced data rates. Antenna design for MIMO systems is a challenging task in any communication system. Theory of characteristic modes (TCM) was proposed to provide some insight into the design and analysis of antennas. This work will focus on the introduction of TCM and will discuss its application in various areas. It will also discuss the application of TCM to printed MIMO antenna design. A systematic method was developed with the help of TCM to predict, whether the isolation between the adjacent MIMO antenna elements with the help of defected ground structures (DGS) can be enhanced or not. On an average 11 dB of isolation enhancement was achieved for the MIMO antennas under consideration. The presence of the slots in the chassis was investigated with the help of TCM, and a 4-element MIMO Slot frequency reconfigurable antenna was presented. The physical mechanism behind frequency reconfigurability with the help of TCM was also investigated. This presentation will also highlight the shortcomings of the TCM approach such as the use of the chassis as a main radiating element and the antenna elements as an exciter for frequencies greater than 2 GHz.

Index Terms: PIFA, Monopole, Slot Antenna, multiple-input-multiple-output (MIMO), Theory of characteristic modes (TCM), chassis.

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Theory of Characteristic modes application to MIMO Antennas