Investigations on Ultrawideband Fractal Microstrip Patch Antenna Arrays for MIMO Wireless Communication Applications

Abstract

Today, people around the globe are acknowledging the significance of wireless technology in their day-to-day activities such as entertainment, education, security and communication. With the tremendous development in the sector of mobile wireless technology (from the current 4G to the upcoming ultra-fast 5G standard), the demand for incorporating high speed, economical, wideband and low-powered ultra-wideband (UWB) antenna in modern wireless devices is increasing substantially. Moreover, the concept of multiple-input multiple-output (MIMO) antenna technology integrated in UWB systems helps to enhance signal-to-noise ratio (SNR) and data transmission speeds in a multipath propagation scenario. The research presented in this thesis addresses the four major constraints namely miniaturization, large bandwidth, high inter-element isolation and band-notch characteristics while modeling portable UWB-MIMO antennas for the advanced integrated systems. For developing small-sized UWB-MIMO antennas, the application of iteratively generated fractal geometries with the notable attributes of self-similarity and space-filling are employed in the antenna designs. The designed compact fractal antenna arrays are incorporated with defected ground structure (DGS), offset feeding, stub loading and slot etching approaches to excite a large band of operation. The decoupling networks, inter-element spacing and DGS geometries play a vital role to overcome the coupling issue between the neighboring radiators in a compact MIMO configuration. At last, to filter out the unwanted interference caused by the existing licensed applications in the operational UWB range, various notch structures are integrated in the array design. Objective 1 presents the modeling, simulation, and experimental analysis of six different dual port MIMO antenna arrays incorporated with different fractals (Sierpinski Gasket, Pythagorean tree, Circular, Koch curve, Koch Snowflake, and Koch Anti-Snowflake) and DGS geometries for UWB characteristics.