Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 28 for “"30 GHz"”.
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30 GHz Switchable Waveguide Antenna: Prototype Antenna Solution for 60 GHz Wi-Fi Protocol 802.11 ad
… of this thesis was to design an antenna for 60 GHz Wi-Fi protocol 802.11 ad. Due to high loss at this frequency, highly directional, narrow beam antennas are required. Therefore, for WLAN applications where hemispherical coverage is required, a multi-antenna-element solution is required. In …
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Total power radiometers at 12, 20 and 30 GHz used in the OLYMPUS experiment at Virginia Tech
… strength of beacons at 12.502, 19.770 and 29.656 GHz on board the OL YMPUS satellite in order to gather space-earth propagation statistics for a period of one year. The radiometers are used to set the clear sky reference levels for the beacon receivers. The paper begins with an overview of radio …
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Rain attenuation and depolarization along 10 to 30 GHz earth space links predicted from s-band dual-polarized radar measurements
… attenuation and cross polarization at 10-30 GHz from dual-polarization radar data with a high degree of accuracy. FORWP uses a rigorous backscattering computer model BSCAT to infer rain drop size distribution along the slant path from radar measured reflectivity and differential …
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A simple model for the depolarizing effects of rain and ice on earth satellite links in the 10 to 30 GHz frequency range
… of dual polarized signals above about 10 GHz. The depolarization versus attenuation relationship is examined in depth using a rigorous multiple scattering model. This relationship for rain is expressed in the form of a simple function similar to that used by the CCIR. Prediction accuracy …
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Characterization of tropospheric scintillations on Earth-space paths in the Ku and Ka frequency bands using the results from the Virginia Tech OLYMPUS experiment
… propagation experiment which includes 12, 20, 30 GHz beacon receivers at an elevation angle of 14° provides us with valuable multi-frequency scintillation data. This dissertation focuses on the characterization of tropospheric scintillations on earth-space paths. Tropospheric scintillations are …
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Gallium Nitride-Based HEMTs for Microwave Power and Noise: Physics and Application
… are investigated. The CW power performance at 20 GHz and 30 GHz of 0.25 mum x 100 mum AlGaN/GaN HEMTs grown by metal-organic chemical vapor deposition (MOCVD) on semi-insulating SiC substrates is reported. Saturated output power at 20 GHz was 6.4 W/mm with 16% power added efficiency (PAE), and …
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Adaptive power control as a fade countermeasure on satellite links
Satellite systems in the 20/30 GHz band are very susceptible to outages due to rain-induced fades. In order to reduce the impact of these fades, it has been proposed that the power of the uplink station transmitter be adjusted during the fade to compensate. This dissertation will explore some of …
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A Novel Variable Inductor-Based VCO Design with 17% Frequency Tuning Range for IEEE 802.11AD Applications
… systems are required to cover a broad 8 GHz TR centered on 60 GHz. This wide TR at V band imposes significant challenge to the VCO design in radio transceivers, and makes the TR of the integrated VCO a major bottleneck to the successful commercialization of many IEEE 802.11ad compliant …
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Fade slope measurements and modeling in the Ku- and Ka-bands using the Olympus satellite
… propagation in the Ku- and Ka-bands. 12, 20, and 30 GHz beacons were transmitted from the Olympus satellite and received at earth stations located in Blacksburg, Virginia. Data were collected from August 1990 through August 1992. One year of useable data were extracted from the measurements for …
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Data acquisition and control system for the OLYMPUS propagation experiments
… satellite that broadcasts coherent at 12, 20 and 30 GHz and is viewed from Blacksburg, Virginia at an elevation angle of 13.9°. This low elevation angle yields a relatively long atmospheric path which serves to accentuate propagation effects. The DACS is a custom design which collects propagation, …
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System requirements for a dual polarized space to earth communications link
… satellite communications links in the 20/30 GHz bands and frequency reuse through orthogonal polarizations. This thesis examines the system level constraints imposed by medium effects at these high frequencies of which the most serious is rain induced attenuation and depolarization. The …
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ACTS radiometers and a comparison of atmospheric attenuation derived form temperature-humidity and radiometric data
… effects caused by the atmosphere for 20 and 30 GHz signals. Each of these terminals contains one total power radiometer for each frequency. These radiometers are used to set clear sky attenuation reference levels for satellite beacon calibration. This thesis describes the design, …
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Frequency scaling of rain attenuation on satellite links in the Ku/Ka-bands using OLYMPUS satellite data
… communications traffic now use C-band (4-8 GHz) and Ku-band (12-18 GHz). The next approved, yet largely unused, frequency allocation for domestic use is in the K-band (18-27 GHz) to Ka-band (27-40 GHz). At these higher frequencies, however, earth-space radio links suffer atmospherically …
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Study of fade and inter-fade durations in Ku- and Ka- band frequencies using OLYMPUS satellite beacons
… obtained from the three beacons at 12, 20, and 30 GHz aboard the OLYMPUS satellite were analyzed. The different types of signal impairments and their causes were highlighted and a literature survey conducted. Twelve months of fade and inter-fade data were analyzed and the results of these …
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Free-Space Measurements of Dielectrics and Three-Dimensional Periodic Metamaterials
… horn antennas with bandwidth from 5.8 GHz to 110 GHz, which are connected to a HP PNA series network analyzer. The dielectric lenses focus the incident beam to a footprint measuring 1 wavelength by 1 wavelength. The sample holder is positioned at the focal point between the two …
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Negative Temperature Programming using Microwave Gas Chromatography
… to wavelengths of 1 cm to 1 m (frequencies of 30 GHz to 300 MHz respectively). Gaisford and Walters developed the microwave GC oven in 2000, which operated at 919 MHz. The microwave GC oven has been engineered to generate a uniform microwave field around an open tubular capillary column with …
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Design of broad-band dual-polarized microstrip patch antennas with high port isolation for millimeter-wave 5G applications
… next generation of 5G communications around 28 GHz. Dual polarization antennas are employed to increase the capacity of the allocated spectrum through frequency reuse. Techniques for improving the impedance bandwidth is one of the most researched areas of microstrip antenna technology. New …
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Miniaturized Antenna for Satellite Broadband Application
… a type of complementary antenna, designed for 26-30 GHz, which is chosen for the application after an extensive survey of wideband, circularly polarized antenna elements. The magneto-electric dipole antenna or MEDA is a broadband antenna and can be made linearly or circularly polarized depending …
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Modulation of coherently coupled surface-emitting laser arrays: analysis and applications
… A record VCSEL 3 dB bandwidth of 37 GHz (receiver limited) is obtained under highly single-mode coherent operation with narrow spectral width and increased output power while the laser array is biased at low current density. Additionally, this result has been duplicated by multiple …
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New techniques for multiple wavelength fiber laser generation based on edfa and tdfa
… is able to generate a microwave signals for 10 GHz, 20 GHz, 30 GHz, and 100 GHz region, respectively.
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