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Project and Study of RF and MW Signals Synchronizers
João Nuno Pimentel da Silva Matos; José Carlos da Silva Neves; Jorge Perez MartinezThe work described in this thesis deals with the study and characterization of synchronization systems used at RF and microwave bands, mainly to achieve symbol synchronization in high bit rate digital communications. First, feedhack systems are studied with special attention given to the phase locked loop with injection (PLLI). Afterwards the problem of syrzchronization of signals with open loop structures is a...
Earth-Satellite Channel Characterisation at 12, 20 and 30 GHz and Frequency Sca...
Armando Carlos Domingues da Rocha; José Carlos da Silva NevesThe Olympus Satellite propagation package, comprising two vertical polarized beacons (12.5 and 30 GHz.) and a dual polarized one at 30 GHZ, is presented and the opportunities offered to characterise the propagation channel discussed. This subject, after a survey of that shows almost no available data and studies are available, is elected as a the main investigation topic of the thesis. (...)Keywords: attenuatio...
Wide-band Radio Propagation Channel Modelling in the Millimetre-wave Band and i...
José Joaquim Gomes Fernandes; José Carlos da Silva NevesThis thesis deals with wide-band propagation channel mollelling in the millimetre-wave band and its impact on the transmission performance of a mobile radio communication system intended to support the range of services envisioned for the B-ISDN. First, it is identified the appropriate frequency band to implement a mobile broadband system and/or a broadband wireless access for indoor environments. (...)keywords...
Study of the Impact of the Antennas on Mobile Broadband Communications in Indoo...
Orlando Fernandes Sousa; José Carlos da Silva NevesThis work presents a study of the impact of the biconic horn, sectored and adaptive antennas on mobile broadband radio communications in indoor environments. The main parameters that characterise the radio propagation channel are introduced, such as, received power and time dispersion, as well us conventional and smart techniques to improve the system performance. All proposed solutions are confirmed via comput...
Characterisation of an Electromagnetic Wave Reflection on Rough Surfaces
Arlindo Manuel de Fontes Marques; José Carlos da Silva NevesThis dissertation deals with propagation channel modelling, namely the characterisation of a diffuse reflection of an electromagnetic wave in a given surface. (...)Keywords: mobile communications; millimetre-waves; ray tracing, specular and diffuse reflection; kirchhoff; field perturbation; phase perturbation; full waveM.S., 1997more info. http://opac.ua.pt/F/?func=find-b&find_code=SYS&REQUEST...
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