Design and evaluation of slot multiple element antennas

MIMO uses multiple element antennas (MEAs) at the transmitter and receiver to exploit spatial channels for improving communications performance such as spectral efficiency and outage. The performance returns for MIMO become significant when the number of antennas at each end of the link becomes large. The challenges in the realization of MIMO lie with both the extra antennas and the extra communications signal processing. In mobile communications, a basic problem is integrating a large number of uncorrelated antenna elements within the mobile terminal. As yet, there are no standard figures of merit or measurement procedures to evaluate the performance of the MIMO antennas. Consequently, MEA designs are often developed in a rather ad hoc way, without a formal measure of how well the antenna system is performing. Parameters such as correlation, diversity gain and capacity are popularly used as metrics for MIMO antenna performance. However, the correlation describes an aspect of the statistical characteristics, the diversity gain assumes a signal combination technique, and the capacity further includes the communications performance. These terms can be attributed to MEA designs, but they do not address important design aspects of the antennas themselves. For example, the compactness and efficiency (which must include the mutual coupling losses) of MEAs for MIMO are undeveloped. This dissertation addresses new MEA evaluation techniques and new types of antennas. New figures of merit for MIMO antennas are proposed, including MEA space efficiency. The evaluation is demonstrated using idealized antennas and slot MEA examples designed in this dissertation. The antennas use the slot elements because of their advantages over other elements types. Contributions include new design information for slot elements as well as new MEA designs using the slot elements.