Design, Modeling and Numerical Analysis of Microwave and Optical Devices: The Multi-band Patch Antenna, Ultra Wideband Ring Filter and Plasmonic Waveguide Coupler
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In this dissertation, three devices are studied and devised for the applications in microwave and optical communication: (1) Multiband Patch Antenna, (2) Ultra-Wideband Band Pass Ring Filter and (3) Plasmonic Waveguide Coupler with High Coupling Efficiency. First, the idea of a simple frequency reconfigurable patch antenna that operates at multiband from 2 GHz to 4.5 GHz is presented; by changing the position of the microstrip connecting elements on the antenna patches, the operating frequency will shift with fixed radiation patterns, which can be utilized in MIMO (Multiple IN Multiple Out) wireless data transmission. Next, a compact ultra-wideband (UWB) single-ring bandpass filter of 8GHz bandwidth with sideband and harmonics suppression achieved by forced boundary condition and step impedance filter is proposed. This approach provides a simple way for the design of ultra-wideband filters. Based on the transmission spectrum, it is known that the group delay variation in the pass-band is smaller than 0.3 ns, which indicates the proposed structure is very suitable for real applications. Finally, a short partially corrugated tapered waveguide for silicon-based micro-slab waveguide to plasmonic nano-gap waveguide mode conversion at the optical communication frequency is investigated. The structure is designed to achieve mode matching between the silicon slabs and plasmonic waveguides. High coupling efficiencies up to 87%~98% are demonstrated numerically. The results show that the corrugated structure will be helpful for realizing full on-chip silicon plasmonic devices.