Thesis (MScEng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The aim of this thesis is the analysis and design of a broadband PIN diode switch. Pin diode switches are gaining popularity in RF and microwave applications today. This is due to their excellent switching and power handling capabilities, reliability, low cost and small size. An analysis and design procedure for broadband PIN diode switch design, using the series, shunt and compound topologies respectively, is presented. In order to do a proper switch design, accurate practical models for the components are required. Parameter extraction therefore formed an important consideration for this study. A parameter extraction procedure is presented, which enables the designer to very accurately extract the required models for the components in the environment they operate in. The designer can then do a proper design to ensure that the switch response when measured, closely corresponds to that simulated. A compound configuration switch was designed, built and measured to confirm the validity of the design procedure. The results illustrate that if the extracted models of the components are integrated into the design, the measured and simulated response compare remarkably well. / AFRIKAANSE OPSOMMING: Die doel van die tesis is die analise en ontwerp van 'n wyeband PIN diode skakelaar. PIN diode skakelaars is besig om meer populariteit te verwerf in hedendaagse RF en mikrogolf toepassings. Dit is as gevolg van die diode se goeie skakel- en drywing hantering vermoëns, betroubaarheid, lae koste en klein fisiese dimensies. 'n Analise en ontwerpsprosedure vir wye band PIN diode skakelaars in die serie, parallel en saamgestelde topologieë word getoon. Om 'n deeglike skakelaar ontwerp te doen, word akkurate en praktiese modele van die komponente benodig. Parameter ekstraksie was daarom 'n groot oorweging vir hierdie studie. 'n Metode om parameters te onttrek word getoon wat die ontwerper in staat stelom akkurate modelle van komponente te onttrek, in die omgewing waarin hulle gebruik word. Die ontwerper kan dan 'n deeglike ontwerp doen wat as dit gemeet word.. die gemete en gesimuleerde resultate goed salooreenstem. 'n Saamgestelde topologie skakelaar is ontwerp, gebou en gemeet om die ontwerpsprosedure te verifieer. Die resultate toon dat as die modelle wat onttrek is, gebruik word in die ontwerp, dan stem die gemete en gesimuleerde resultate baie goed ooreen.

Thesis (PhD (Electric and Electronic Engineering))--University of Stellenbosch, 2005. / A tunable X-band PIN diode switch, implemented in evanescent mode waveguide, is presented. To allow in-situ tuning of resonances after construction, a novel PIN diode mounting structure is proposed and verified, offering substantial advantages in assembly costs. Accurate and time-effective modelling of filter and limiter states of the proposed switch is possible, using an evanescent mode PIN diode and mount model. The model is developed by optimizing an AWR Microwave Office model of a first order switch prototype with embedded PIN diode, to simultaneously fit filter and limiter measurements of four first order prototypes. The model is then used in the design of a third order switch prototype, achieving isolation of 62 dB over a 8.5 to 10.5 GHz bandwidth in the limiting state, as well as reflection of 15.73 dB and insertion loss of 1.23±0.155 dB in the filtering state over the same bandwidth.

Thesis (PhD)--Macquarie University, Faculty of Science, Dept. of Physics & Engineering, 2008. / "March, 2009". Bibliography: p. 145-158.

"March, 2009". / Thesis (PhD)--Macquarie University, Faculty of Science, Dept. of Physics & Engineering, 2008. / Bibliography: p. 145-158. / Introduction -- Frequency selective surfaces -- Absorb/transmit frequency selective surface absorber -- Switchable frequency selective surface for wireless applications -- Energy-saving glass characterisation -- Frequency selective surface solution for energy-saving glass -- Conclusion. / This thesis presents three topics related to frequency selective surfaces (FSSs), namely bsorb/transmit FSSs, active FSSs and passive bandpass FSSs for energy-saving glass used in modern buildings. These three FSSs are unique in their design and functionalities. The absorb/transmit FSS is a novel dual-layer frequency selective surface for 5 GHz WLAN applications. This FSS can stop propagation of specific bands by absorbing as opposed to re ecting, while passing other useful signals. This is in contrast to the conventional Salisbury and Jaumann absorbers, which provide good absorption in the desired band while the out-of-band frequencies are attenuated. The second topic is a single-layer bandpass active FSS that can be switched between ON and OFF states to control the transmission in 2.45 GHz WLAN applications. Previously, researchers have focused on the bandstop and dual-layer versions of the active FSS. This is in contrast to the design presented in this thesis which is single-layer and provides extra advantage in a practical WLAN environment. Also the dc biasing techniques that were used for the active FSS design are easier to implement and provide good frequency stability for different angles of incidence and polarisations in both ON and OFF states. The last topic is on the use of a bandpass FSS in energy-saving glass panels used in building design. The manufacturers of these glass panels apply a very thin metal-oxide coating on one side of the glass panels to provide extra infrared (heat) attenuation. However, due to the presence of the coating, these energy-saving glass panels also attenuate communication signals such as GSM 900, GSM 1800/1900, UMTS and 3G mobile signals etc. This creates a major communication problem when buildings are constructed with windows of this glass. In this thesis, a solution to this problem is presented by designing and etching a cross-dipole bandpass FSS on the coated side of the glass to pass the useful signals while keeping infrared attenuation at an acceptable level. One of the advantages of this FSS design is that measured material values of the metal-oxide coating are used for simulations, which have not been done previously. / Mode of access: World Wide Web. / 166 p. ill. (some col.)