Finite-Difference (FD) based complex modes solver and Complex Mode Matching Method (CMMM) is one of the most popular combinations in modeling and simulation of opti- cal waveguides. This thesis covers the basic theories behind the approaches and impor- tant implementation details. Weighted Optical Path Distance is proposed to speed up convergence and improve numerical accuracy to deal with asymmetric structures. An improved formula is derived for Complex Mode Matching Method expansion process based on matrix optimization. The latter part applies the above approach in the mod- eling of bending structures and grating structures. Typical structures, including bend- ing structures, straight-bend-straight structures, long-period gratings, gratings with de- posited layer, gratings with deep corrugations, are investigated and analyzed. / Thesis / Master of Science in Electrical and Computer Engineering (MSECE)

Yes / A novel 50μm Silicon-based on-chip antenna is presented that combines metamaterial (MTM) and substrate integrated waveguide (SIW) technologies for integration in THz circuits operating from 0.28 to 0.30 THz. The antenna structure comprises a square patch antenna implemented on a Silicon substrate with a ground-plane. Embedded diagonally in the patch are two T-shaped slots and the edges of the patch is short-circuited to the ground-plane with metal vias, which convert the structure into a substrate integrated waveguide. This structure reduces loss resulting from surface waves and Silicon dielectric substrate. The modes in the structure can be excited through two coaxial ports connected to the patch from the underside of the Silicon substrate. The proposed antenna structure is essentially transformed to exhibit metamaterial properties by realizing two T-shaped slots, which enlarges the effective aperture area of the miniature antenna and significantly enhances its impedance bandwidth and radiation characteristics between 0.28 THz to 0.3 THz. It has an average gain and efficiency of 4.5dBi and 65%, respectively. In addition, it is a self-isolated structure with high isolation of better than 30dB between the two ports. The on-chip antenna has dimensions of 800×800×60 μm3. / H2020-MSCA-ITN-2016 SECRET-722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E0/22936/1

<p> A detailed theoretical analysis of the propagation constant and the field components in rectangular waveguide completely filled with a semiconductor subjected to an external transverse applied magnetic field, has been carried out. A numerical solution of the transcendental equation for the propagation constant has been obtained for the n-type germanium samples with different conductivities and magnetic fields. </p> <p> An experimental verification of this theoretical analysis has been made with a 22.2 ohm-em, n-type germanium sample at 9.46 GHz. The applied transverse magnetic field was varied from 0 to 10 Kilogauss. Measurements of the reflection co efficients at the air-semiconductor interface for different values of the applied magnetic field have been made with a high precision microwave reflection bridge. The experimental results agree well with the theoretical results. </p> / Thesis / Master of Engineering (MEngr)

Разработка излучателя на основе волновода специальной формы. Щелевые волноводные излучатели находят широкое применение как в качестве элементов антенных решеток или облучателей апертурных антенн, так и в виде самостоятельных излучателей. Излучатели на основе прямоугольного волновода используется достаточно давно и их характеристики подробно исследованы. Но современные требования к антенным системам приводят к необходимым решениям ряда вопросов при использовании щелевых излучателей в волноводах специальной формы. В данной работе приведены результаты электродинамического расчета щелевых излучателей в некоторых разновидностях таких волноводов. / Development the radiator on the base of waveguide special form. Slotted waveguide radiators are used in construction for antennas elements arrays, irradiators reflector antennas, or for separate radiators. Radiators on the rectangular waveguide are explored many years ago. But modern requirements to antenna systems are leading to many questions, which we using slotted radiators in the waveguide special form. In this work you can see the results of electrodynamics calculation slotted radiators in some types of this waveguides.

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