The departure from strict periodic order in two-phase dielectric materials can offer properties that are otherwise inaccessible to perfectly ordered photonic crystals. Herewith, we investigate the circular dichroism of the single gyroid photonic crystal in the presence of spatial distortions. FDTD simulations and microwave transmission measurements on 3D-printed replicas show that certain harmo...

Propagation of the extremely short electromagnetic pulse in non-linear dielectric media without the slowly varying envelope approximation is discussed. The models under consideration take into account both resonant and not-resonant excitations of non-linear medium, and polarisation states of electromagnetic wave. Steady state solutions of the relevant equations are presented for certain of thes...

We formulate a general theory of the dielectric response of a lattice with a structural transition and a polarisation instability due to a soft-optic mode coupled to low energy electronic excitations by the electromagnetic fields. The electronic excitations considered are in two-limits; those of a low density of free-electrons or those of a low density of strongly localised electrons in the Cou...

The oil/paper insulation system in a transformer degrades under various chemical, thermal and electromechanical stresses during its operation. Dielectric response measurements like the Return Voltage Measurement (RVM) and Polarisation and Depolarisation Current (PDC) measurement are currently being used for condition assessment of the insulation. In the current research project, the ageing cond...

We rigorously derive the leading order terms in asymptotic expansions for the scattered electric and magnetic fields in the presence of a small object at distances that are large compared to its size. Our expansions hold for fixed wavenumber when the scatterer is a (lossy) homogeneous dielectric object with constant material parameters or a perfect conductor. We also derive the corresponding le...

Preventative diagnosis and maintenance of transformers has become more popular in recent times in order to improve the reliability of electric power systems. A number of transformers have recently been tested using Return Voltage (RV) and Dielectric Dissipation Factor (tanδ) measurements in the time and frequency domain, respectively. This paper outlines a circuit model which describes the diel...

When unpolarised light is reflected from a smooth dielectric surface, it is spontaneously partially polarised. This process applies to both specular and diffuse reflection, although the effect is greatest for specular reflection. This paper is concerned with exploiting this phenomenon by processing images of smooth dielectric objects to recover surface normals and hence height. The paper presen...

Dielectric constant and loss in liquid-ammonia solutions of alkali halides have been measured in the frequency range 0.7 — 70 GHz. At least one relaxation process exists in this frequency range in addition to the relaxation of the solvent molecules. The additional relaxation is ascribed to the orientational polarisation of ion pairs. The concentration of the ion pairs, calculated with a special...