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Full-Text Articles in Engineering
Infrared Tapered Slot Antennas Coupled To Tunnel Diodes, Louis A. Florence
Infrared Tapered Slot Antennas Coupled To Tunnel Diodes, Louis A. Florence
Electronic Theses and Dissertations
Tapered slot antennas (TSAs) have seen considerable application in the millimeter-wave portion of the spectrum. Desirable characteristics of TSAs include symmetric E- and H-plane antenna patterns, and broad non-resonant bandwidths. We investigate extension of TSA operation toward higher frequencies in the thermal infrared (IR), using a metal-oxide-metal diode as the detector. Several different infrared TSA design forms are fabricated using electronbeam lithography and specially developed thin-film processes. The angular antenna patterns of TSA-coupled diodes are measured at 10.6 micrometer wavelength in both E- and H-planes, and are compared to results of finite-element electromagnetic modeling using Ansoft HFSS. Parameter studies are …
Design Of A Wideband Dual-Polarized Cavity Backed Slot Antenna, Rajesh Paryani
Design Of A Wideband Dual-Polarized Cavity Backed Slot Antenna, Rajesh Paryani
Electronic Theses and Dissertations
A new technique for designing wideband dual-polarized cavity-backed slot antennas is presented. The structure is in the form of a double-resonant, dual-polarized slot antenna backed by a shallow substrate integrated cavity with a depth of approximately one tenth the free space wavelength. The presence of the cavity behind the slot enhances the antenna's directivity and reduces the possibility of surface wave propagation in the antenna substrate when the element is used in an array environment. Moreover, the dual-polarized nature of this radiating element may be exploited to synthesize any desired polarization (vertical, horizontal, RHCP, or LHCP). The double-resonant behavior observed …
Saw Reflective Transducers And Antennas For Orthogonal Frequency Coded Saw Sensors, Bianca Maria Santos
Saw Reflective Transducers And Antennas For Orthogonal Frequency Coded Saw Sensors, Bianca Maria Santos
Electronic Theses and Dissertations
Passive sensors that vary its impedance per measured parameter may be used with surface acoustic wave (SAW) reflective transducers (SRT) for wireless acquisition of the measurand. The device is composed of two transducers, where one, which may be attached to an antenna, is used to launch the wave within the device substrate, and the other is where the sensor load is attached to. The latter is able to reflect the incident wave. How much power is reflected is determined by the attached sensor load. Amplitude variations as well as peak frequency variations of the SRT reflectivity response are explored in …
Demonstrating Reflectarray Behavior At Infrared, James Ginn
Demonstrating Reflectarray Behavior At Infrared, James Ginn
Electronic Theses and Dissertations
Reflectarrays are traditionally passive, planar microstrip antenna devices designed for reflected phase manipulation at each individual antenna element making up the array. By varying the phase response across the surface with the antenna elements, reflectarrays allows a planar surface to exhibit electromagnetically an arbitrary geometry, such as a spherical surface. Initially proposed as a low-cost replacement for bulky parabolic reflectors, reflectarrays have been successfully developed and utilized at both RF and millimeter-wave frequencies. From the standpoint of an optical systems designer, adapting low-frequency reflectarray technology to develop a sub-millimeter and infrared reflectarray (SMIR) would provide a highly desirable alternative to …
Transmission Lines For Ir Signal Routing, Tasneem Mandviwala
Transmission Lines For Ir Signal Routing, Tasneem Mandviwala
Electronic Theses and Dissertations
In this dissertation, the design, fabrication, and characterization of coplanar striplines, vias, and microstrip lines is investigated, from the point of view of developing interconnections for antenna-coupled infrared detectors operating in the 8- to 12-micron wavelength range. To our knowledge, no previous efforts have been made to study the performance of metallic-wire transmission lines at infrared frequencies. Both the design and fabrication of these structures present unique challenges. Because of attenuation and dispersion issues, the analytical formulas for transmission-line parameters that are valid below a few hundred GHz are not applicable in the infrared. Therefore, numerical modeling was performed to …
Liquid Crystal Optics For Communications, Signal Processing And 3-D Microscopic Imaging, Sajjad Khan
Liquid Crystal Optics For Communications, Signal Processing And 3-D Microscopic Imaging, Sajjad Khan
Electronic Theses and Dissertations
This dissertation proposes, studies and experimentally demonstrates novel liquid crystal (LC) optics to solve challenging problems in RF and photonic signal processing, freespace and fiber optic communications and microscopic imaging. These include free-space optical scanners for military and optical wireless applications, variable fiber-optic attenuators for optical communications, photonic control techniques for phased array antennas and radar, and 3-D microscopic imaging. At the heart of the applications demonstrated in this thesis are LC devices that are non-pixelated and can be controlled either electrically or optically. Instead of the typical pixel-by-pixel control as is custom in LC devices, the phase profile across …
Modified Sierpinski Fractal Antenna, Tripti Luintel
Modified Sierpinski Fractal Antenna, Tripti Luintel
Electronic Theses and Dissertations
Fractal antennas have the potential to provide multi-band solution through the property of self similarity that the fractal shape possess. This thesis deals with some modifications of the original Sierpinski fractal patch antenna, providing additional parameters to optimize in order to get the required radiation characteristics. A systematic study of the original Sierpinski monopole was done to gain an insight on the operation and multi-band behavior of the antenna and a similar study was done to find out why the patch version of Sierpinski lacks multi-band behavior. A Sierpinski antenna is designed by merging a grid and the fractal restoring …