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Wireless power transmission (WPT) is currently being used in a number of applications, including monitoring the health of concrete infrastructure such as bridges, buildings, tunnels, and dams, where antennas of different types, geometries and sizes have been designed for powering sensors that are embedded in concrete structures. However, dielectric resonator antennas (DRAs), which have shown great potential in free-space for microwave WPT applications, have not been investigated in concrete. In this thesis, different DRAs are designed and their performance in the X-band frequency range for the WPT in concrete is investigated using an electromagnetic computational tool: CST Microwave Studio (MWS). In addition, selected DRAs are manufactured and measurement results are compared to simulation results. Furthermore, CST MWS is utilised to design and investigate surface-mountable electromagnetic sensors that can be used for concrete characterisation, crack location and crack width estimation. Firstly, rectangular DRAs of different lengths operating in the X-band are designed, and a two-antenna setup with an external transmitting antenna and an embedded receiving antenna is used to investigate WPT to embedded sensors in concrete. It is found that, the designed DRAs can be used for WPT to the embedded sensors in concrete. However, it is also found that some of the electromagnetic energy from the external transmitting antenna radiates away from the embedded antenna. Short and long DRAs are fabricated and measured in free-space and a good agreement with simulation results is observed. The short DRA has better WPT performance than long DRA over the entire X-band. To achieve a reliable WPT system, the sensitivity of the WPT to variations in the electrical (loss tangent tan δ and the relative dielectric constant) of concrete is investigated. It is found that WPT ii using the long and short DRAs appear to be more sensitive to the electrical properties of concrete at frequencies that are closer to the lower and upper frequency limits, respectively. Secondly, gratings techniques are used to redirect the radiated electromagnetic energy from the transmitting antenna towards the receiving antenna. For this purpose, rectangular-, hexagon-, and octagon-shaped DRAs with metal loaded dielectric gratings are designed, investigated, and optimised to maximise microwave WPT to embedded sensors in concrete. These antennas are suitable for wireless powering of multiple sensors, which is illustrated by changing the positioning of the embedded/receiving antenna with respect to the transmitting antenna. Furthermore, the sensitivity of WPT using these antennas to variations in the electrical properties of concrete is investigated and the simulation results are recorded. The obtained results show that reliable WPT can be obtained with the octagon-shaped DRA because it is less sensitive to variations in the electrical properties of concrete. Finally, surface-mountable electromagnetic sensors using dual-port rectangular DRA, hexagon-, and octagon-shaped planar DRAs are designed and investigated for characterisation of concrete and crack detection. It is found that the surface-mountable electromagnetic sensor using the rectangular DRA has the highest sensitivity to variations of the electrical properties of concrete and can be used to approximate the loss tangent and the relative dielectric constant of concrete, whereas hexagon-shaped planar DRA is highly sensitive to the crack width at different locations, and can be used to estimate crack width and position remotely.

Development of a computational model to study the interaction of high frequency electromagnetic (EM) waves with plasmas is presented. The plasma is described using a fluid model which is a multi-species, multi-temperature continuum representation with nite rate chemistry. The governing equations in the plasma module comprise the conservation laws for species number densities, electron energy and heavy species energy. The EM waves are described using the classical Maxwell's equations. The plasma governing equations are discretized in space using the finite volume method and the backward Euler method is used for temporal discretization. Maxwell's equation are represented as a second order curl-curl equation for the electric fi eld which is discretized in space using the Nédélec finite elements of first type and discretized in time using the backward Euler method. Linear system of equations arising out of the discretization is solved using Krylov subspace methods, typically the GMRES algorithm. A preconditioner based on nodal auxiliary subspaces of H(curl) space and Multigrid algorithms is used for the curl-curl equation. This preconditioner accelerates the convergence of the Krylov method and provides a mesh and time-step independent convergence rate. Preconditioners for time-harmonic Maxwell's equations is also studied. A two-level preconditioner comprising the shifted Laplacian preconditioner and deflation preconditioner is developed and its performance for different problem sizes and frequencies is reported. The developed wave-plasma model is used to simulate the following physical problems. First is the simulation of gas breakdown and transient evolution of plasma in a direct current microdischarge. The study also simulates the effect of active external electron injection into the discharge from the electrode surfaces. The time scales of switching the plasma between the pre-injection and the post-injection steady state is found to be approximately 1 [mu]s. The second problem is the simulation of a microdischarge and its interaction with a high frequency EM wave propagating in a wave guide. This study is focused on understanding different regimes in wave-plasma interactions. The nature of wave propagation in an under-dense and over-dense plasma medium is reported. The over-dense plasma medium interacts strongly with the propagating wave and the epsilon-zero resonance is observed. The final problem considered is the simulation of plasma breakdown and evolution in a two cylindrical Dielectric Resonator (DR) structure. The spatial structure of the plasma at different instants of discharge evolution is examined. The evolving plasma medium acts as a lossy medium to the propagating wave and damps the resonance in the DR structure thereby providing a pathway for stable steady state operation.

Development of a computational model to study the interaction of high frequency electromagnetic (EM) waves with plasmas is presented. The plasma is described using a fluid model which is a multi-species, multi-temperature continuum representation with nite rate chemistry. The governing equations in the plasma module comprise the conservation laws for species number densities, electron energy and heavy species energy. The EM waves are described using the classical Maxwell's equations. The plasma governing equations are discretized in space using the finite volume method and the backward Euler method is used for temporal discretization. Maxwell's equation are represented as a second order curl-curl equation for the electric fi eld which is discretized in space using the Nédélec finite elements of first type and discretized in time using the backward Euler method. Linear system of equations arising out of the discretization is solved using Krylov subspace methods, typically the GMRES algorithm. A preconditioner based on nodal auxiliary subspaces of H(curl) space and Multigrid algorithms is used for the curl-curl equation. This preconditioner accelerates the convergence of the Krylov method and provides a mesh and time-step independent convergence rate. Preconditioners for time-harmonic Maxwell's equations is also studied. A two-level preconditioner comprising the shifted Laplacian preconditioner and deflation preconditioner is developed and its performance for different problem sizes and frequencies is reported. The developed wave-plasma model is used to simulate the following physical problems. First is the simulation of gas breakdown and transient evolution of plasma in a direct current microdischarge. The study also simulates the effect of active external electron injection into the discharge from the electrode surfaces. The time scales of switching the plasma between the pre-injection and the post-injection steady state is found to be approximately 1 [mu]s. The second problem is the simulation of a microdischarge and its interaction with a high frequency EM wave propagating in a wave guide. This study is focused on understanding different regimes in wave-plasma interactions. The nature of wave propagation in an under-dense and over-dense plasma medium is reported. The over-dense plasma medium interacts strongly with the propagating wave and the epsilon-zero resonance is observed. The final problem considered is the simulation of plasma breakdown and evolution in a two cylindrical Dielectric Resonator (DR) structure. The spatial structure of the plasma at different instants of discharge evolution is examined. The evolving plasma medium acts as a lossy medium to the propagating wave and damps the resonance in the DR structure thereby providing a pathway for stable steady state operation.