Dr Cameron Gallagher

I am an experimental physicist in the electromagnetic and acoustic metamaterials group that has developed a speciality in characterisation of composite materials across the microwave region.

I am interested in the electromagnetic properties of composite materials and how they may be tailored to suit applications in microwave technologies such as antenna systems.

Post-Graduate Research

I graduated from Exeter University's CDT for metamaterial research, performing an investigation into the microwave characteristics of particulate magnetic composites. The aim of the project was to use 'onion skin' microparticles to better understand the way in which magnetic domains are formed and how they may be utilised to increase the frequency at which significant permeability may be achieved.

Post-Doctorate Research

Since graduating I have taken on a role as post-doctoral research fellow at The University of Exeter. I previously worked on a NATEP project, developing a broadband AMC design for use with conformal antennas. This work was undertaken in collaboration with Technical Composite Systems and Cobham Aerospace Connectivity and was successful in producing an AMC prototype in-house that was designed subject to specific constraints provided by industrial partners. This project has lead to a second NATEP project, again working with Technical Composite Systems, this time to produce impedance matched composite materials for low-cost miniaturisation of antennas.

I have recently been performing an investigation into how microwave metasurfaces may be utilised in the food industry for improving the efficiency of cooking in conventional microwave ovens. This work is performed in partnership with QinetiQ, as part of TEAM-A, The Tailored Electromagnetic and Acoustic Materials Accelerator and is funded in part by an industrial partner, Pepsico.

I am now working part-time on a research project within SYMETA, Synthesising 3D Metamaterials for RF, Microwave and THz Applications. This work is undertaken in collaboration with EPSRC, University of Oxford, Loughborough University, Queen Mary University of London and The University of Sheffield. The project aims to investigate the ways in which additive manufacturing technology can be exploited to create novel, multi-functional 3D metamaterials.

Publications

D. Bychanok et al. “Exploring Carbon Nanotubes / BaTiO₃ / Fe₃O₄ Nanocomposites as Microwave Absorbers” PIER C, vol. 66, pp. 77 – 85, (2016).
doi:10.2528/PIERC16051106

Barr L. E. et al. “Investigating the nature of chiral near-field interactions”, Physical Review B, volume 97, no. 15, article no. ARTN 155418 (2018)
doi:10.1103/PhysRevB.97.155418.

C. P. Gallagher et al. “A Broadband Stripline Technique for Characterizing Relative Permittivity and Permeability” IEEE Trans. Mic. Tech. vol. 67, pp. 231 – 238, (2019)
doi:10.1109/TMTT.2018.2851563

Magnetic composite and particulate systems have a paramount importance in modern technology, ranging in applications from magnetic recording media to RF communication. In order to broaden the impact and value of these microwave devices, it is essential that research is undertaken to explore how the permeability of these materials can be increased, and to increase the operational frequency and bandwidth over which they have useful magnetic properties. As part of this work, we will also seek to understand and control the permittivity and loss of these materials, for example, for the design of low reflectivity surfaces and impedance matched materials for antenna design.

The aim of this project is to explore experimentally the static and dynamic electromagnetic properties of particulate magnetic composites. We will look at the magnetic properties of single particles, including their domain structure, as a function of their size, shape and crystalline structure: as part of this we will consider what contribution to the electromagnetic properties that dynamic processes such as domain wall oscillations and FMR provide. Having understood this, we will examine their collective response as part of a bulk composite in order to engineer materials designed with bespoke permittivity and permeability parameters. The experiments will be carried out using state-of-the-art synchrotron and neutron facilities, and static magnetometry and microwave techniques. The former, such as XPEEM, will be used to image directly the magnetic structure of a single particle and its dynamic response to the RF excitation, whereas VNA measurements, using strip-line permeameters, will provide broad-band measurement of the electromagnetic parameters of manufactured composites. We will also employ other lab-based tools to understand the main magnetic characteristics (i.e. hysteresis, anisotropy, saturation magnetisation, bulk moment) of the composite.