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 8 of 8 for “"Frequency tunability"”.
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Dynamic tunability enhancement of reflectarray antenna using non-homogeneous dielectric materials
… study provides a thorough investigation on the tunability performance of reflectarrays designed in X-band frequency range. The objective of this work is to demonstrate the functionality of an active reflectarray antenna with optimized loss performance and enhanced dynamic phase range. Different …
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Development of switchable planar reflectors for beam shaping realization
… of planar reflectors within X-band and Ku-band frequency ranges. The objective of this work was to investigate the feasibility of using strategic slot embedded patch element configurations for an efficient reconfigurable reflectarray antenna design. PIN diodes were incorporated with single and …
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New modeling of compact, high-efficiency, and widely-tunable gas-phase terahertz lasers
… intrinsically low efficiency, not tunable in frequency, and large sizes. In this thesis, we introduce a compact, frequency-tunable source of terahertz radiation with high efficiency. We first present both an innovative theoretical model and experimental validation of a Methyl Fluoride OPFIR …
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Long-wave infrared frequency combs based on quantum cascade lasers
… as trace-chemical sensing, health monitoring, frequency metrology, noninvasive imgaing and infrared countermeasures. The LWIR region (or mid-infrared region), roughly ranging from 2-20 [mu]m, is of particular importance to spectroscopy applications, since many molecular species have their …
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Micromachined Components for RF Systems
… a reverse-side exposure technique, showing a tunability of 33% at 10V. It shows an improved Q-factor of 21.5. Reduced IMD capacitors consist of wide RF gaps and narrowly spaced high resistivity electrodes with a gap of 2um and a width of 2um within the wide gap. A 14um gap and a 20um gap …
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High-resolution infrared spectroscopy of large molecules and water clusters using quantum cascade lasers
… An accurate value for the gas phase vibrational frequency of the donor bend was also obtained, which was found to be quite similar to previous theoretical predictions obtained from an ab initio potential energy surface. Details of the construction of an external cavity QCL (EC-QCL) system are …
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Filter Design for Interference Cancellation for Wide and Narrow Band RF Systems
In radio frequency (RF), filtering is an essential part of RF transceivers. They are employed for different purposes of band selection, channel selection, interference cancellation, image rejection, etc. These are all translated in selecting the wanted signal while mitigating the rest. This can be …
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Design and Implementation of Reconfigurable and MIMO Antennas for Future Heterogeneous Wireless Systems
… suffer from bandwidth limitations and restricted frequency rarge. Onekey approach to overcome this problem without significantly affecting the antenna size is to apply antenna tuneability and reconfigurability. This is achieved by electronically changing some properties of the antenna usually by …