Date of Award

5-25-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Systems Engineering

First Advisor

Hussain Al-Rizzo

Abstract

Due to the fast development of wireless communication applications, the study of Multiple Input Multiple Output (MIMO) communication systems has lately gained comprehensive research interests since it can significantly increase the channel capacity and link reliability without sacrificing bandwidth and/or power transmitted. However, the user equipment is constantly shrinking in size to support more applications and satisfy aesthetic needs, which increases the need for more compact, high-performance antenna array designs. Many techniques are being constantly developed to combat the effects of mutual coupling that arise with the miniaturization of MIMO arrays. This dissertation focuses on designing, testing, and evaluating new MIMO antenna arrays that are intended for 5G, Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I), Vehicle-to-Everything (V2X), and Wi-Fi applications using different mutual coupling suppression techniques. Two novel V2X monopole antenna arrays that utilize unique Defected Ground Structures (DGS) that are constructed around the feed-points in the ground plane of two vertical wire monopoles separated by 8 mm (λ/10.7) and 12 mm (λ/5.5) operating at 3.51 GHz and 3.9 GHz, respectively. Furthermore, vertical and planar miniaturized antenna arrays are introduced for 5G and Wi-Fi 6 that utilize a single Frequency Selective Surface (FSS) to significantly reduce the mutual coupling between the antenna elements which are separated by 8 mm (λ/10.14) at 3.7 GHz for the vertical monopole antenna array and 3 mm (λo/18.8) edge-to-edge separation at 5.32 GHz for the planar microstrip antenna array. The single FSS is next used to tune the frequency of two reconfigurable vertical monopoles separated by 8 mm (λ/10.4) to operate from 3.59 GHz to 3.77 GHz while keeping low levels of mutual coupling. All the MIMO antenna designs presented in this dissertation demonstrate a significant reduction in mutual coupling below -20 dB while keeping an impedance matching level below – 10 dB. Some of the antennas presented in this dissertation are additionally analyzed in realistic indoor and outdoor environments using Ray-Tracing (RT) and Stochastic Channel Modeling (SCM) tools to evaluate their MIMO channel capacity performance. Lastly, results from RT and SCM tools are compared in terms of the MIMO channel capacity using a complete description of the antennas at the transmitting and receiving ends in terms of 3D polarimetric radiation patterns and scattering parameters. The performance is evaluated for 5G New Radio (NR) services and V2X systems to provide information regarding the capabilities and limitations of each approach under different channel environments and the Quality of Service (QoS) for high data rate and low latency content delivery in the 5G NR sub-6 GHz mid-band Frequency Range-1 (FR1) N77/N78 bands.

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