MIMO Antenna Modelling Using the Effective Length Matrices

A hybrid electromagnetic-network analysis of the antennas-channel multiple input multiple output (MIMO) communication subsystem is presented. The analysis is based on the antenna effective and realized effective length matrices, which relate in a compact mathematical way the radiated and received electric field intensities to the network characteristics of actual and coupled transmitting (Tx) and receiving (Rx) multi-element antenna (MEA) systems. The effective length matrices are calculated via the active power gain and phase antenna patterns obtained by means of any full wave computational electromagnetics (CEM) field solver. It is shown that the realized effective length matrix is suitable for the S-parameter analysis of a MIMO communication link, while the effective length matrix is convenient for its Z-parameter analysis. The effective length matrix framework is applied to a free space 2x2 coupled dipoles MIMO system and its results are in excellent agreement to those obtained by a Method of Moments (MoM) based field solver.