Efficient discrete modelling of axisymmetric radiating structures

This thesis describes research on Efficient Discrete Modelling of Axisymmetric Radiating Structures . Investigating the possibilities of surmounting the inherent limitation in the Cartesian rectangular Transmission Line Modelling (TLM) method due to staircase approximation by efficiently implementing the 3D cylindrical TLM mesh led to the development of a numerical model for simulating axisymmetric radiating structures such as cylindrical and conical monopole antennas. Following a brief introduction to the TLM method, potential applications of the method are presented. Cubic and cylindrical TLM models have been implemented in MATLAB and the code has been validated against microwave cavity benchmark problems. The results are compared to analytical results and the results obtained from the use of commercial cubic model (CST) in order to highlight the benefit of using a cylindrical model over its cubic counterpart. A cylindrical TLM mesh has not previously been used in the modelling of axisymmetric 3D radiating structures. In this thesis, it has been applied to the modelling of both cylindrical monopole and the conical monopole. The technique can also be applied to any radiating structure with axisymmetric cylindrical shape. The application of the method also led to the development of a novel conical antenna with periodic slot loading. Prototype antennas have been fabricated and measured to validate the simulated results for the antennas

Transmission line modelling of cylindrical cavity loaded with a slotted dielectric rod

© 2015 IEEE. This paper examines the effect of loading a microwave cylindrical cavity with radially slotted dielectric rod. Although, methods for the computation of the resonant frequency of dielectric loaded cavity have been presented in the literatures, the effect of placing radial slots on axisymmetric dielectric load in relation to the cavity resonance has not been studied. The study was carried out using a cylindrical TLM solver developed in MATLAB. A parametric check on the effect of varying the slot depth and width shows that the slot width has greater effect on the cavity resonance than the slot depth. It was also discovered that multiple narrow slots on the load affects the resonance frequency of the cavity more than a single wide slot. The effect of periodicity of the slots on the resonance frequency was also investigated

Effect of annular slots on the solid conical antenna

The effects of adding annular slots to solid conical antenna is described in this paper. The slots produced stop-bands with anti-resonant frequencies that are inversely proportional to the depth of the slots. The addition of double slots produced two distinct stop-bands. Prototype antennas were fabricated and measured to verify the simulated results

Effect of annular slots on the solid conical antenna

The effects of adding annular slots to solid conical antenna is described in this paper. The slots produced stop-bands with anti-resonant frequencies that are inversely proportional to the depth of the slots. The addition of double slots produced two distinct stop-bands. Prototype antennas were fabricated and measured to verify the simulated results