Abstract
Previous studies have investigated communications between regions of space and have considered the effect of antenna volume in determining the theoretical capacity of multiple-input multiple-output (MIMO) communications systems. In this paper the effects of antenna (1)volume on available bandwidth for MIMO systems is considered. It is demonstrated that while higher order modal connections can be established even for small antennas that a fundamental limitation on bandwidth exists. This limitation becomes important for ultra-wide band (UWB) communications systems.