Analytical models for the multiplexing of worst case traffic sources and their application to ATM traffic control.

Postprint (published version

E-plane parallel coupled resonators for waveguide bandpass filter applications

High skirt selectivity and extended out-of-band rejection is a major challenge for the successful progress of in-line microwave filters. This thesis presents novel filter realizations with improved performance, compatible with the standard single thin all-metal insert in a split-block housing and therefore maintaining the low-cost fabrication characteristics. In addition, significant filter performance improvement is achieved. The synthesis procedure implemented for the filter concept consists of a few steps. Some preliminary steps are a rigorous characterization of a double-ridge coaxial waveguide, and the modelling of an equivalent circuit model for the parallel coupled ridge waveguide devised in the filter concept. From these elements, a full wave electromagnetic analysis shows that parallel-coupled asymmetric ridge waveguides produce strongly dispersive coupling which introduces a transmission zero. Later on this property is extended to parallel-coupled asymmetric ridge waveguide resonators, where it is demonstrated that it is possible to independently control the coupling coefficient and the frequency of the transmission zero. This allows the realization of pseudo-elliptic narrowband in-line bandpass filters in E-plane technology. A general synthesis procedure for high order filters is outlined and numerical and experimental results are presented for validation. The elements employed for the synthesis procedure of the bandpass prototypes are also applied to investigate structures suitable for different applications. In particular, stopband and dual stopband filters are presented with numerical and experimental results. Finally, the study of a microwave chemical/biochemical sensing device for the characterization and detection of cells in chemical substances and cells in solution in micro-litre volumes is also reported.Engineering and Physical Sciences Research Council(EPSRC

Data distribution satellite

A description is given of a data distribution satellite (DDS) system. The DDS would operate in conjunction with the tracking and data relay satellite system to give ground-based users real time, two-way access to instruments in space and space-gathered data. The scope of work includes the following: (1) user requirements are derived; (2) communication scenarios are synthesized; (3) system design constraints and projected technology availability are identified; (4) DDS communications payload configuration is derived, and the satellite is designed; (5) requirements for earth terminals and network control are given; (6) system costs are estimated, both life cycle costs and user fees; and (7) technology developments are recommended, and a technology development plan is given. The most important results obtained are as follows: (1) a satellite designed for launch in 2007 is feasible and has 10 Gb/s capacity, 5.5 kW power, and 2000 kg mass; (2) DDS features include on-board baseband switching, use of Ku- and Ka-bands, multiple optical intersatellite links; and (3) system user costs are competitive with projected terrestrial communication costs

Critical Connections: Communication for the Future

The U.S. communication infrastructure is changing rapidly as a result of technological advances, deregulation, and an economic climate that is increasingly competitive. This change is affecting the way in which information is created, processed, transmitted, and provided to individuals and institutions. The report analyzes the implications of new communication technologies for business, politics, culture, and individuals, and suggests possible strategies and options for congressional consideration