PhD Studentship: Time Varying Metasurfaces: Exploring Spectral Control and Overcoming Bandwidth Constraints

Summary:

The University of Exeter’s Centre for Metamaterials Research and Innovation (CMRI) with industry partners Leonardo, is inviting applications for a fully funded PhD studentship. For eligible students, the studentship will cover fees, stipend and project costs. The stipend will be paid at the UKRI rate, plus an additional £2000 top-up per year. There is an enhanced budget for project costs (including travel) of £5000 per year. The student will be based in the Department of Physics and Astronomy in the College of Engineering, Mathematics and Physical Sciences at the Streatham campus in Exeter.

Research Proposal

Current metamaterials function through structuring matter on a small enough scale to change its macroscopic properties. Periodically patterning a surface, for instance with metal and dielectric yields a ‘metasurface’ that can behave as neither of its constituents: e.g. as an effective “artificial” magnetic conductor [Sievenpiper, et al.], which has found use in the design of compact and conformal antenna systems.

While metamaterial concepts enable remarkable properties that are often difficult to achieve via conventional routes, there remain immovable constraints in functionality – for example - no metasurface can change the frequency of an incident wave. Furthermore, the maximum bandwidth of any passive absorber is fixed by its thickness and magnetic properties [Rozanov]. It would be a significant advance if we could avoid these constraints, perhaps by conceiving a metasurface that not only reshapes the radiation pattern of a nearby antenna but also changes its operation band. 

One way to overcome these constraints is to impose structuring in not only space, but also time. 

This project will investigate the potential of time varying metasurfaces for controlling antenna radiation. For this we must consider building metasurfaces out of elements with properties that can be switched very rapidly – such fast switching (on the order of the wave period) gives new functionality where the frequency spectrum of the field can be modified. We will explore the physics of time varying metasurfaces realised in the RF and microwave domain, where the effective material parameters can either be varied optically, or electronically.

The project will be a mix of theory and experiment, investigating the theoretical potential of time varying metamaterials, in particular the possibility to overcome size/bandwidth limitations and shape radiation in both frequency and space, while also developing the experimental capability to realise time varying metasurfaces in the laboratory, using fast electronics and Schottky and pin-diodes, as well as optically modulated semiconductors.

About the Centre for Metamaterial Research and Innovation:

You would be joining the doctoral training programme at the Centre for Metamaterial Research and Innovation (CMRI) at the University of Exeter. We provide scientific knowledge as well as transferable and technical skills training to all our students to prepare them for careers within and outside of academia.

Exeter's Centre for Metamaterials Research and Innovation (CMRI) is a community of academic, industrial, and governmental partners that harnesses world-leading research excellence from theory to application, and enables simulation, measurement, and fabrication of metamaterials and metamaterial-based devices. Our breadth of research is our centre's strength: our PhD students, researchers and academics solve multi-faceted research questions and challenges.  

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