Design and Development of Multiband Antennas for Portable Devices with MIMO Implementation

Includes bibliographical references (pages 105-106).The goal of this thesis is to design and develop a multiband antenna which can be\ud used in portable devices such as tablets. The antennas cover majority of practical wireless communication bands. The antennas were also implemented in MIMO (multiple input multiple output) configuration to increase the data throughput. The antennas show near omnidirectional patterns as well as acceptable antenna efficiency which is essential for any wireless communication system. Full wave analysis of antennas was performed using Ansys High Frequency Structure Simulator (HFSS) v15 software. First of all, two multiband printed loop antennas covering lower GSM 850MHz (824-890MHz), GSM 900MHz (880-960MHz) frequency bands and higher GSM 1800MHz (1710-1880MHz), GSM 1900MHz (1850-1990MHz), UMTS 2100MHz(1920-2170MHz), LTE 700MHz (698-787MHz), LTE 2300MHz (2305-2400MHz), LTE 2500MHz (2500-2690MHz), Wi-Fi 2.4GHz (2400-2483.5MHz) communications bands were designed and developed on the FR4 printed circuit board (PCB). To evaluate the performance, the antenna was conceptualized and simulated on a small ground plane size. Various simulation results such as impedance matching, 2D/3D radiation patterns, antenna efficiency, peak gain, etc., are included for the antennas. Once the satisfactory results were obtained, it was implemented on a tablet size (241mm X 186mm) ground plane.\ud Studies were also performed on 2X2 MIMO arrangement on the same circuit space.\ud The envelope correlation coefficient (ECC) was calculated using S-parameters as well as radiation pattern measurement based techniques. Other parameters necessary for MIMO performance such as total active reflection coefficient (TARC), channel capacity, mean effective gain (MEG), capacity loss were also computed based on the simulated and measured data for the final antenna selection. The 2X2 MIMO antenna was prototyped, and experimentally verified to validate the simulation results. Available discrepancy between the simulated and measured results is due to the fabrication and measurement errors