CDT in Metamaterials: Effect of Non-Conductive Material Dielectric Permittivity and Geometrical Features on Electromagnetic Surface Wave Propagation - Ref 3916

Statement of Research

- Supervisors: Professor J Roy Sambles, Professor Alastair P Hibbins, University of Exeter
- External Supervisor: Dr Jasmin Stein, TWI Ltd

The SurFlow™ technology recently developed and patented by TWI (GB2522344A and US10090715B2) offers a great solution for replacing wired communication in complex systems, such as vehicles. For example, today’s luxury cars contain 1,500 copper wires, totalling ~1 mile in length. In addition, with electrification and automation of vehicle complexities will increase even further. SurFlow™ is a technology where the composite structure itself is used for data communication. Information is carried by electromagnetic surface waves (See Figure 1) and data speeds are three times faster than standard Cat5e Ethernet cable, and because the signal is bound to the structure, it is much more secure than Wi-Fi.

In order to make a composite compatible for surface wave propagation the composite needs to have a dielectric layer on one side and a conductive layer on the opposite side. The main function of the conductive later is to reflect electromagnetic waves that have been introduced to the composite with the correct incident angle to the opposite surface of the composite. The function of the dielectric layer is to create an interface for the signal to propagate. Both the resin and the composite are dielectric materials. However, they have difference dielectric permittivity, which creates the required interface for the signal propagation.

The understanding of the effect of the change in the dielectric permittivity is critical when deciding whether an existing structure is compatible with SurFlow™. The study mainly focuses on glass fibre composites with different resin types. These will be thermoset resin and thermoplastic resins, hence of relevance to, for example, aerospace and automotive industries. Resins with varying dielectric permittivity will be used for the assessment. Experiments will be carried out in an anechoic chamber to eliminate any interference and reflected airwaves.

The successful applicant will benefit from the expertise of the R&D team responsible for the SurFlow™ technology, led by Dr Jasmin Stein, combined with cutting edge academic insight from researchers at the University of Exeter. As part of Exeter’s Centre for Metamaterial Research and Innovation, Profs Hibbins and Sambles have been studying surface waves in the microwave and RF regime for nearly 20 years. Their work is associated with the control of energy propagation through local control of the surface impedance boundary condition. This is achieved either with surface patterning, through regular, random or spatially-graded geometries, or via the use of overlayers.

This project will be a mix of analytical, numerical, fabrication and characterisation work, and a will be suited to applicants that are keen to work on industry problems with a rigorous academic approach. The successful candidate will be keen to engage with all aspects of the project, be strongly motivated to lead their own investigations, have excellent computational and experimental skills, and able to communicate information clearly to a broad audience.

The objectives of this PhD project are to:

- Understand the effect of dielectric/composite interface on the signal propagation;
- Understand the effect of composite/conductive layer interface on signal propagation;
- Understand the effect of conductivity of the carbon fibres on the out of plane evanescent filed distribution;
- Understand the effect of conductivity of the carbon fibres on the signal incident angle;
- Understand the effect of carbon fibre weave architecture on the signal propagation;
- Understand the effect of carbon fibre on airwave leakage and electromagnetic interference;
- Develop an electromagnetic surface wave propagation model at meso-scale level (interface).

The student would be involved in the following activities:

- Carry out a literature review on electromagnetic surface wave propagation and the effect of conducting materials;
- Experimental design, including design of experiments approach, and set-up;
- Develop a method for evaluating the out-of-plane evanescent field distribution;
- Explore the effect of the interface between the dielectric and the conductive composite on the evanescent field and the signal propagation
- Explore the effect of the carbon fibre architecture on the signal propagation
- Develop an EMSW propagation model, which consists of material conductivity, and interface properties.

Further information is available on the University’s website http://www.exeter.ac.uk/studying/funding/award/?id=3916.