Design and analysis of wideband passive microwave devices using planar structures

A selected volume of work consisting of 84 published journal papers is presented to demonstrate the contributions made by the author in the last seven years of his work at the University of Queensland in the area of Microwave Engineering. The over-arching theme in the author’s works included in this volume is the engineering of novel passive microwave devices that are key components in the building of any microwave system. The author’s contribution covers innovative designs, design methods and analyses for the following key devices and associated systems: Wideband antennas and associated systems Band-notched and multiband antennas Directional couplers and associated systems Power dividers and associated systems Microwave filters Phase shifters Much of the motivation for the work arose from the desire to contribute to the engineering o

Synthèse et réalisations avec des zéros de transmission de filtres planaires miniaturisés à topologies fractales en substrat suspendu

Ce mémoire s'attache à proposer de nouvelles structures de filtrage planaires grâce aux itérations fractales et utilisant la technologie du substrat suspendu. Une technique de synthèse est développée. Elle permet dans un premier temps de caractériser les circuits prototypes passe-bas et passe-bande équivalents du filtre à concevoir. La matrice des coefficients de couplages peut ainsi être extraite à partir éléments des circuits équivalents. La synthèse permet de développer des filtres a réponse asymétrique, avec des zéros de transmission à gauche ou à droite de la bande passante, grâce aux rétro-couplages entre résonateurs non-adjacents. Les simulations électromagnétiques effectuées sous Momentum (ADS) permettent de caractériser les résonateurs miniaturisés fractals (facteur de qualité a vide, sensibilité aux tolérances...) et de déterminer les coefficients de couplages en fonction des gaps qui les séparent. Deux itérations fractales sont étudiées: l'itération de Minkowski appliquée à un résonateur bimode carré et l'itération de Hilbert appliquée à un résonateur linéique. Les résultats montrent surtout la possibilité de supprimer le premier harmonique grâce à ces itérations. Cinq exemples de réalisations sont montrés. Des filtres compacts avec de fortes rejections hors bande passante ont ainsi pu être conçus. Les résultats de mesure valident la synthèse et justifient l'intérêt de la miniaturisation par itération fractale.This thesis focuses on the development of new planar filtering structures using fractal iterations with the suspended substrate technology. A synthesis method is developed. It allows the characterization of equivalent lowpass and bandpass filter prototypes. The theoretical coupling coefficients matrix is extrapolated from the equivalent circuits' elements. The synthesis allows the development of asymmetrical frequency characteristics, with transmission zeroes on both sides of the passband, thanks to cross-couplings between non-adjacent resonators. Electromagnetic simulations carried out using Momentum (ADS) allow us to characterize miniaturized fractal resonators (unloaded quality factor, sensitivity...) and to determine the coupling coefficients along with their gap spacings. Two fractal iterations are studied; the Minkowski iteration is applied to a dual-mode square resonator and the Hilbert resonator is applied to a linear half-wavelength resonator. Results show the possibility to suppress the first harmonic thanks to these iterations. Five examples of realizations are presented. Compact filters with high out of band rejections are obtained. Measurement results validate the synthesis procedure and justify the interest of miniaturized filters using fractal iterations

Applied Mathematics to Mechanisms and Machines

This book brings together all 16 articles published in the Special Issue "Applied Mathematics to Mechanisms and Machines" of the MDPI Mathematics journal, in the section “Engineering Mathematics”. The subject matter covered by these works is varied, but they all have mechanisms as the object of study and mathematics as the basis of the methodology used. In fact, the synthesis, design and optimization of mechanisms, robotics, automotives, maintenance 4.0, machine vibrations, control, biomechanics and medical devices are among the topics covered in this book. This volume may be of interest to all who work in the field of mechanism and machine science and we hope that it will contribute to the development of both mechanical engineering and applied mathematics