No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Solar power is a clean, renewable source of energy. There is a growing demand for cheap, high efficiency photovoltaic cells. Of the many emerging solar harvesting technologies, a concept that has not been widely explored is that of optical antennas. In 1972 Bailey et al.[1] explored scaling down of antenna technology to match the solar spectrum. A recent review was given by Lukas Novotny et al.[2], in which they outline the major hurdles as being the lack of reliable nano-fabrication and an inability to rectify into the Tera-hertz frequencies band. Presently we aim to fabricate photovoltaic cells that incorporate an array of vertically aligned metallic nano-rods (MNR). Porous aluminum oxide (PAO) is used as a nano-structured template for growth of the MNR. PAO exhibit vertically aligned pores (D = 20 - 200nm) in a densely packed hexagonal arrangement. MNR fabrication is achieved through templated electrochemical deposition, and investigated with SEM and VIS-IR spectroscopy. MNR samples have been specifically designed to be incorporated as a photoactive material for a novel photovoltaic cell. Through fine control of their length, the MNR excitation energy can be tuned to the visible spectrum. Excitation of the MNR leads to energy transfer with localized acceptor molecules, creating a rectification of the field. The fabrication of MNR helps progress the development of the proposed antenna photovoltaic device. [1] R. L. Bailey, “A Proposed New Concept for a Solar-Energy Converter," Journal of Engineering for Power, pp. 73-77, Apr. 1972. [2] P. Bharadwaj, B. Deutsch, and L. Novotny, “Optical Antennas," Advances in Optics and Photonics, vol. 1, pp. 438-483, May 2009. / Thesis (Master, Chemistry) -- Queen's University, 2013-01-07 12:36:57.17

International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / This paper describes a ferrite antenna that can produce any polarization on the Poincaré sphere over the frequency range of 9.0 to 11.4 GHz by utilizing Faraday rotation and a quarter-wavelength phase shifter. All possible polarizations of the electromagnetic wave are achievable with this antenna which includes linear, circular and elliptical polarizations. Any tilt angle of elliptical polarization and any orientation of the linear polarization can be achieved as well. The polarization of the ferrite antenna can be electronically switched to a different polarization instantly without the use of moving parts. An automatic data acquisition system was designed and built to fully analyze the antenna' s characteristics.

International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / This paper describes a C-band auto-tracking receiving system on shipboard which is used in satellite telemetry. The system consists of receiving antenna, wideband feed, antenna pedestal, telemetry/tracking receiver antenna controller and computer console. Its characteristics are as follow: Single Channel Single Pulse Tracking Feed, 2. 5m Antenna Diameter, 500MHz BW, LHCP and RHCP Dual - Channel Polarization Diversity Receiving. The servo system uses rate - gyros as stabilized element being based on the micro - processor to realize the digital servo control. Computer console performs the status monitoring and management to the whole system. The system design, the main system specification and important test results are given.

Terahertz technology is rapidly growing for applications in various fields such as medical sciences, remote sensing, material characterization, and security. This accelerated growth has motivated engineers to develop compact, portable, and cost-effective terahertz sources and detectors. Terahertz generation and detection can be achieved using photoconductive antennas (PCAs), which have unique advantages. Notably, they do not require a vacuum or cryogenic cooling to function. PCAs operate on the principle of photoconductivity, which allows for compact integration with a fiber optic laser. It is also possible to launch THz radiation to a waveguide, which can be used for making a robust THz spectroscopy system. Ultra-short laser pulses are available in both 800 nm and 1550 nm wavelengths. However, the 1550 nm window has distinctive advantages such as availability of fiber amplifiers and fiber based electro-optical components at a relatively lower cost. The goal of this research is to introduce cost-effective and state-of-the-art solutions to develop THz transceivers for use in terahertz time-domain spectroscopy (THz-TDS) at 1550 nm wavelength. In this thesis we explore three approaches for enhancing THz emission and reception using PCAs. First, an array of hexagonal shape plasmonic nano-structures was used to increase the optical field coupling to the minimum depth of the substrate. Next, nano-structures also helped with enhancing the local electric field inside a low-cost semi-insulating GaAs substrate. This technique resulted in a 60% enhancement of the THz emission compared to a commercial LT-GaAs based PCA with antireflection coating. Moreover, the plasmonic nano-structures efficiently remove heat from the gap area allowing for operation at higher bias voltages. Plasmonic structures on LT-GaAs were investigated, which use a mid-gap Arsenic defect state to absorb 1550 nm light. The plasmonic devices were found to outperform existing InGaAs substrate based THz devices by factor of two. Finally, optimization of the LT-GaAs growth and annealing conditions was investigated to maximize the THz signal at 1550 nm. Outcomes of this research pave the way for designing cost-effective THz transceivers for time domain Terahertz spectroscopy systems at 1550 nm wavelength. / Graduate