  The problem addressed in this study is how to design and test compact antenna
arrays for portable Mulitple-Input Multiple-Output (MIMO) transceivers. Mutual
coupling in an antenna array affects signal correlation and array radiation
efficiency - both of which have dramatic consequences for MIMO channel
capacity. Mutual coupling becomes more pronounced as array aperture shrinks and
is therefore a critical issue in compact array design. Two novel compact arrays
are designed and fabricated for use in MIMO enabled mobile devices. These
arrays are extremely compact yet demonstrate acceptable mutual coupling and
radiation efficiency because of the MIMO-specific criteria used during their
design. An experimental methodology is presented for fair and meaningful
characterization of MIMO arrays by field trial. This methodology addresses the
issue of capacity normalization and quantifies how well an antenna array's
radiation pattern interfaces with multipath propagation. Results are presented
from an extensive measurement campaign in which a true MIMO transceiver testbed
is outfitted with compact arrays and dipole arrays of various sizes. A
comprehensive and fair comparison is made between the compact arrays and dipole
arrays in a variety of indoor propagation scenarios. Design recommendations for
compact MIMO arrays are given.
