Date of Award

2-7-2024

Document Type

Thesis

School

School of Electrical & Electroncis Engineering

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Dr.Ramya Vijay

Keywords

Reconfigurable Intelligent Surface, Reconfigurable Metasurface, Simultaneous Transmission and Reflection Metasurface, Reflecting Intelligent Surface, Smart City

Abstract

The potential new applications and increasing demands of future 5th generation (5G) and beyond wireless communication indicate a promising future for mobile communications. However, the transmission medium has traditionally been seen as an unpredictable factor between the sender and receiver. As we enter the digital era of wireless communications, signal quality is deteriorating due to environmental interferences.

With the continuous advancement of technology, there is an increasing need for advanced solutions that can handle complex applications such as haptic communications, the Internet of Things for smart cities, automation, and manufacturing. One technology that has received much attention is the reconfigurable metasurface for reconfigurable intelligent surfaces (RIS). Using reconfigurable metasurfaces provides benefits such as low cost, low power consumption, and improved communication coverage and quality. The RIS demands simple configuration, angular stability, and polarisation insensitivity.

Over the past twenty years, there has been significant advancement in the concept of metasurface, leading to unprecedented possibilities. The initial version involved regular homogeneous periodic structures, notably impacting various application fields, from radio to optical frequencies. Subsequently, a second generation comprising inhomogeneous quasi-periodical or gradient-like arrangements emerged. This spatial modulation enhanced capabilities by offering more degrees of freedom.

Finally, the third generation includes thin patterned structures with controllable properties in space and time through different control mechanisms and advancements in integration technologies, such as electronic, optical, thermal, chemical principles and liquid crystal-based methods. These developments enable the creation of tunable programmable structures for diverse applications. This research will present a design of third generations metasurface with a detailed focus on reconfigurable techniques.

This article introduces a reconfigurable combined loop metasurface, operating at 15.48 GHz covering the Ku band, that can effectively characterize the EM response. This is achieved by incorporating PIN diodes in the meta-atoms on a periodic array within a single-layer metallic structure. By controlling the state of the PIN diodes, the metasurface can achieve various performances viz phase reconfigurability, simultaneous transmission & reflection modes of operation. The proposed structure has validated a 32 × 32 metasurface through numerical simulations and experiments that exhibit promising results, demonstrating its potential for use in 6G applications.

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