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 14 of 14 for “"Bandwidth Enhancement"”.
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Bandwidth enhancement techniques for low-profile antennas: Theory and experiment
This thesis describes techniques for bandwidth enhancement for low-profile antennas. The first method involves the use of coupled resonators. In particular, two cavity-backed slot antennas are coupled through an aperture in a common wall. One cavity-backed slot antenna, of the coupled antenna …
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Modulation of coherently coupled surface-emitting laser arrays: analysis and applications
… and computational power, data transmission bandwidth is required to increase exponentially as well. Furthermore, as data centers become physically larger, utilizing more interconnects and requiring longer rack-to-rack fiber transmission distance, low power consumption and narrow spectral …
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Simulation of strongly injection-locked semiconductor ring lasers
To overcome the limited modulation bandwidth of directly modulated semiconductors, a novel scheme for modulation bandwidth enhancement and tailoring is presented. This scheme involves a single-frequency master laser monolithically integrated with strongly injection-locked whistle-geometry …
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Modal and radiation characteristics of the crossed-septum dielectric loaded waveguide for wideband applications
… support single-mode propagation over the desired bandwidth. This dissertation presents a novel method of obtaining bandwidth enhancement of a square waveguide using both dielectric loading and mode filters that retains the 90 degree rotational symmetry. By placing two orthogonal dielectric slabs …
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Enhanced digital modulation of coherently coupled vertical cavity laser arrays: theory and application
… there is an ever-increasing need for high-bandwidth, low-power, and low-cost laser sources. An ideal laser source would have data-rates exceeding 100 Gb/s, energy-per-bit ratios reaching less than 1 pJ/bit, and be fabricated/integrated using conventional methods. In this dissertation, …
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Ultra-wideband miniaturized microstrip patch antennas for wireless communications: design guidelines and modeling
… systems like ultra-wideband (UWB) require larger bandwidth than what is normally utilized with traditional antenna techniques. The interest for compact consumer electronics is growing in the meantime, creating a demand on efficient and low profile antennas which can be integrated on a printed …
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High-Speed Modulation of Semiconductor Lasers and Modulators
… and has drawbacks such as chirping and low bandwidth. To improve the high-speed performance of a single laser, we intensively study the injection locking technique. It is shown that this technique greatly reduces chirping, improves modulation bandwidth, and is very useful for …
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Anomalous Nature Of Metamaterial Inclusion and Compact Metamaterial-Inspired Antennas Model For Wireless Communication Systems. A Study of Anomalous Comportment of Small Metamaterial Inclusions and their Effects when Placed in the Vicinity of Antennas, and Investigation of Different Aspects of Metamaterial-Inspired Small Antenna Models
… WLAN 2.45 GHz band while the DGS has provided bandwidth enhancement in WiMAX and upper WLAN frequency bands, keeping the radiation pattern stable. The next class of antenna is a compact cloud-shaped monopole antenna consisting of a staircase-shaped DGS has been proposed for UWB operation ranges …
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Improving ultrasonic imaging using novel coded excitation techniques
… the axial resolution depends on the source bandwidth. Recently, a novel coded excitation and pulse compression technique, known as Resolution Enhancement Compression (REC), was developed. REC enhances the -6 dB bandwidth of an ultrasonic imaging system. In this dissertation, the limitations …
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Electrically-Small Antenna Performance Enhancement for Near-Field Detuning Environments
Bandwidth enhancement of low-profile omnidirectional, electrically-small antennas has evolved from the design and construction of AM transmitter towers eighty years ago to current market demand for battery-powered personal communication devices. Electrically-small antenna theory developed with …
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A novel technique for phased array receivers based on an economic sampling scheme
… However, these approaches increase the system bandwidth, multiplying it by a factor of $N$ (Number of antennas), as they use redundant information. In this thesis, a novel phased receiver, based on an economic sampling scheme is proposed. All the elements in an array receive a common …
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Towards High-Performance Reflectarray Antennas: Phase Sensitivity Reduction for Wide Bandwidth
… and lightweight design. However, their limited bandwidth poses a significant challenge because phase behavior varies across different frequencies. This thesis aims to address this limitation by proposing methods to widen the bandwidth while maintaining antenna performance. The research begins …
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High-Speed and Power Efficient Integrated Electro-Optic Modulators
… of internet traffic. Therefore, to enhance the bandwidth and to reduce the power consumption I demonstrated two SOI platform-based device architectures in this thesis: one based on the Mach-Zehnder interferometer (MZI) silicon modulator to enhance the bandwidth and the other on the microring …
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Inter-cell interference coordination in 5G ultra-dense networks
… is combined with two promising capacity and bandwidth enhancement techniques - massive multiple input and multiple output (MIMO) and carrier aggregation (CA), for overall network performance. In particular, for the proposed novel NOMA-CA approach, we justify the importance of maintaining …