In this thesis, transmitted reference pulse cluster (TRPC) structure is proposed for low data rate ultra-wideband (UWB) communications to meet the short delay lines and low complexity requirements. TRPC contains closely and uniformly spaced pulses, and makes the analog delay lines short and easy to implement. The performance of TRPC over II B channels is analyzed, simulated and compared to that of three existing techniques: conventional TR. non-coherent pulse position modulation (NC-PPM), and frequency shifted reference (FSR) systems. We demonstrate the performance superiority of TRPC over all those systems. especially when implementation issues such as low complexity are taken into consideration. Moreover, novel schemes are proposed to address the physical layer design issues of the TRPC structure. Based on the theoretical bit error rate (BER) derivation for TRPC, three low complexity integration interval determination schemes requiring no channel state information are developed and simulated. In addition, an adaptive threshold method is developed for the TRPC system. which dynamically calculates the optimal detec¬tion threshold for the auto-correlation receiver, and achieves substantial performance gains over all UWB channel models.

The performance of orthogonal pulse position modulation (PPM) and non-orthogonal pulse position modulation (NPPM) is studied and compared with different ultra wideband (UWB) channel models. Time hopping (TH) is used to decrease the effect of interference in multi access environments. Rake receiver is studied as an ideal UWB receiver for multiuser environments. It is shown that an ideal rake (I-Rake) receiver has the best performance among all rake receivers, followed by 5 finger selective rake (5S-Rake), 5 finger partial rake (5P-Rake), 2 finger selective rake (2S-Rake), and 2 finger partial rake (2P-Rake). With a large number of users, NPPM can achieve a better bit error rate (BER) performance than PPM. It is also shown that PPM and NPPM in a triple Saleh-Valenzuela (TSV) channel has performance similar to that in a Saleh-Valenzuela (SV) channel.

A microwave reflectometer is an instrument to measure a complex ratio between reflected and incident waves at an input port of a uniform transmission line that is terminated in a Device Under Test (DUT). The conventional reflectometer is formed by a four-port network with two ports connected to a microwave source and DUT, and the remaining ports coupled to a heterodyne receiver which acts as a Complex Ratio Detector (CRT). By using the heterodyne receiver technique, the two microwave signals at the input to CRT are converted in the linear manner to an Intermediate Frequency (IF) of hundreds of kHz where they are processed using digital means. As the ratio of two original microwave signals has to be preserved at IF, a very advanced electronic circuitry is required to accomplish the linear conversion process. This complicated electronic circuitry leads to a large size of the conventional reflectometer and its high price tag. Many applications require compact-size and low-cost reflectometers. They can be built using N-port networks, with N being greater than 5, equipped only in scalar (power) detectors. The thesis describes the concept of a multi-port reflectometer which determines the complex reflection coefficient of DUT with the use of scalar detectors instead of the complex ratio detector. It is shown that this device can be designed using an assembly of linear circuits in the form of quadrature (Q) and/or divider (D) hybrids. Assuming ideal operation of these components, it is shown that the reflection coefficient of DUT can be determined using simple mathematical operations on the power values measured by scalar detectors. Alternatively, it can be obtained from the intersection of power circles in a complex reflection coefficient plane. These simple mathematical expressions can be used to obtain an approximate real-time operation of reflectometer. For more accurate results, the multi-port has to be calibrated using calibration standards. A review of full calibration methods for a multi-port reflectometer is presented. In order to obtain wideband performance, the multi-port reflectometer has to be formed by components all having wideband performance. To obtain its low manufacturing cost, these components should preferably be of planar format and lead to a full integration of reflectometer. The thesis investigates a variety of planar couplers and dividers which can offer wideband performances. However, not all of them can lead to a fully integrated multi-port reflectometer. In order to overcome this shortfall, a multilayer microstrip-slot technique is proposed and investigated to obtain wideband components that can lead to a full integration of multi-port reflectometer. It is demonstrated that through the use of multilayer microstrip-slot technique, ultra wideband microwave 3-dB couplers and two-way dividers of in-phase or out-of-phase type can be designed. It is shown that the chosen configurations of dividers are compatible with the 3-dB couplers so that a fully integrated reflectometer can be formed. This compatibility is accomplished through the use of suitably designed microstrip to slotline transitions. An attractive feature of the designed couplers and dividers is that they are of sub-wavelength size and thus are very compact. A fine operation of these components is demonstrated via full electromagnetic wave simulations and experimental tests over and ultra wide frequency band of 3.1 to 10.6 GHz. Rogers substrate RO4003 featuring a relative dielectric constant of 3.38 and a loss tangent of 0.0027 is chosen as a microwave substrate for the design of these components. The design and analysis are carried out with the commercially available full EM simulator CST Microwave Studio while the experimental tests are done with the Vector Network Analyser, HP8510C. By using these components, an ultra wideband complex ratio measuring unit (CRMU), which is the heart of a multi-port reflectometer, is designed. This CRMU is fully integrated and of compact size. Its operation over an ultra wide frequency band is demonstrated via simulations. A particular attention is paid to its real-time mode of operation. Using this mode of operation, the complex ratio of two waves can be displayed on an oscilloscope using an analog electronics performing simple mathematical operations on the measured powers by detectors. While discussing the operation of CRMU, the attention is paid to the location and spacing of power circles centres (q-points) which are used for geometrical interpretation of operation of this device. Good operation of CRMU in this approximate operation mode indicates that the device will operate very well when it is fully calibrated. For simulations of CRMU, CST Microwave Studio, Agilent’s Advanced Design System (ADS) and MATLAB software are applied. Having accomplished the successful design of CRMU, the last step includes the formation of a fully integrated multi-port reflectometer. To this purpose an extra circuitry including multilayer microstrip-slot 3-dB couplers is added to CRMU. The purpose of this additional circuitry is to reroute the incident and reflected signals from the DUT to the input ports of CRMU. A few configurations of multi-port relectometer formed by multilayer microstrip-slot couplers or dividers are investigated via simulations with respect to real-time mode of operation. Then, the best performing configuration is selected for the final development. The device is manufactured in Rogers RO4003 substrate. Its S-parameters are measured with HP8510C analyser and compared with the simulated values. Having obtained a relatively good agreement between the simulated and measured results, the device is calibrated using multiple calibration standards. Its operation is verified for selected DUTs by comparing the measured reflection coeffcients with those obtained using the conventional VNA (HP8510C) over an ultra wide frequency band. A relatively good agreement is obtained between the two sets of measured results. The obtained results prove that the multilayer microstrip-slot technology can successfully be used for the development of a compact low-cost and fully integrated UWB multi-port reflectometer. Because of its compact size and good electrical performance, this device can be used in many microwave sub-systems offering a limited space for implementation of microwave measurements. The thesis shows that the accomplished multi-port device can also be used to build UWB communication transceivers. The concept of such UWB transceivers is addressed in the final sections of this thesis.

Thesis (M.Eng)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: p. 169-170.

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 130-135). Also available in electronic format on the Internet.

Thesis (M.E.-Res)--University of Wollongong, 2008. / Typescript. Includes bibliographical references: leaf 69-75.

Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Manos M. Tentzeris; Committee Co-Chair: John Papapolymerou; Committee Member: Andrew F. Peterson; Committee Member: Chang-Ho Lee; Committee Member: John D. Cressler; Committee Member: Joy Laskar.

Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Aug. 14, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Communications, Department of Electrical and Computer Engineering, University of Alberta." Includes bibliographical references.

Thesis (M.E.E.)--University of Delaware, 2005. / Principal faculty advisor: Leonard J. Cimini, Dept. of Electrical and Computer Engineering. Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 92-95). Also available in electronic version.