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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Front-end considerations for next generation communication receivers

Roy, Mousumi January 2011 (has links)
The ever increasing diversity in communication systems has created a demand for constant improvements in receiver components. This thesis describes the design and characterisation of front-end receiver components for various challenging applications, including characterisation of low noise foundry processes, LNA design and multi-band antenna design. It also includes a new theoretical analysis of noise coupling in low noise phased array receivers.In LNA design much depends on the choice of the optimum active devices. A comprehensive survey of the performance of low noise transistors is therefore extremely beneficial. To this end a comparison of the DC, small-signal and noise behaviours of 10 state-of-the-art GaAs and InP based pHEMT and mHEMT low noise processes has been carried out. Their suitability in LNA designs has been determined, with emphasis on the SKA project. This work is part of the first known detailed investigation of this kind. Results indicate the superiority of mature GaAs-based pHEMT processes, and highlight problems associated with the studied mHEMT processes. Two of the more promising processes have then been used to design C-band and UHF-band MMIC LNAs. A new theoretical analysis of coupled noise between antenna elements of a low noise phased array receiver has been carried out. Results of the noise wave analysis, based on fundamental principles of noisy networks, suggest that the coupled noise contribution to system noise temperatures should be smaller than had previously been suggested for systems like the SKA. The principles are applicable to any phased array receiver. Finally, a multi-band antenna has been designed and fabricated for a severe operating environment, covering the three extremely crowded frequency bands, the 2.1 GHz UMTS, the 2.4 GHz ISM and the 5.8 GHz ISM bands. Measurements have demonstrated excellent performance, exceeding that of equivalent commercial antennas aimed at similar applications.
22

Low Velocity Impact and RF Response of 3D Printed Heterogeneous Structures

Keerthi, Sandeep January 2017 (has links)
No description available.
23

Flíčková anténa s budicí štěrbinou / Centre-fed microstrip patch antenna

Jireček, Martin January 2011 (has links)
Systems with extreme bandwidth are part of advanced modern systems at radio high capacitive communication. Originally this technology was intended for radar scan. Thanks to wide frequency band had radar possibility „ see" a behind crimp, e.g. behind woody partitions etc . To his noise immunity, fail safe tapping plus small wattage heftiness began use for datal systŽm function. If is elementary antenna compound from coaxial probe and shorting outlet, it is possible use to actuating separate narrow slot placed in the middle of incandescent dabs. Impedance and radiating characteristics conventionally plumbed phlobaphene antennae excited tape lead and suggested microstrip phlobaphene antennae are experimentally explored plus collated. Explored is so and effect changes slotted longitude slot on characteristics elementary antenna.

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