Design and analysis of two port MIMO antennas with wideband isolation

Abstract

Ultrawideband (UWB) technology has rapidly gained popularity and demand for recent wireless communication systems after the allocation of 3.1- 10.6 GHz by the Federal Communications Commission (FCC) for UWB applications. Since then, a myriad of research opportunities and challenges exist for the design of UWB antenna systems for application in high speed wireless devices. Multiple-Input-Multiple-Output (MIMO) systems provide a significant increase in channel capacity without the need of additional bandwidth or transmit power by deploying multiple antennas for transmission to achieve an array gain and diversity gain, thereby improving the spectral efficiency and reliability. Since MIMO systems employ multiple antennas, they require high decoupling between antenna elements. Overall UWB MIMO systems require a high isolation of less than -16 dB and also a compact size for compatibility with integrated circuits. This thesis focuses on the analysis and design of MIMO antennas with a compact planar profile that have an operating range in the entire UWB (3.1- 10.6 GHz) and desired antenna performance characteristics. This dissertation presents the work on the design of two- element MIMO antennas and various isolation structures and mechanisms to reduce the mutual coupling between the two elements, out of which two major antenna designs are proposed and analyzed separately for their isolation, bandwidth and radiation characteristics. Both MIMO antenna systems have a significant operating bandwidth covering almost the entire UWB and together with the proposed isolation structures are able to achieve isolation more than -16 dB.