A novel antenna made of a spiral wire wrapped into a larger helical shape is introduced. The geometry of this antenna, which is a doubly helical structure, is fully described by five independent parameters, including two radial dimensions, two pitch angles, and the number of turns. Radiation properties of this antenna are examined both theoretically and experimentally. The Numerical Electromagnetic Code (NEC-2) is used to obtain simulation results. A large number of cases with different radii, pitch angles, and number of turns are investigated. Results for far-field patterns, gain, axial ratio, and bandwidth are presented. The influence of parameters on radiation properties are examined. Several prototypes of the antenna were constructed and tested using an outdoor antenna range. Measured far-field patterns are presented over a wide range of frequencies. The measured and computed radiation patterns are in good agreement. The results of this study indicate that the proposed antenna provides circular polarization and high gain over a wide frequency range. For example, when the number of turns is 10, a gain of 11-14 dB, a boresight axial ratio of less than 3 dB, and a half-power beamwidth of about 40 degrees are achieved over a 30% bandwidth. The side-lobe level for most cases examined is better than 10 dB below the main beam. A unique advantage of this antenna is its much smaller size compared with a conventional helical antenna made of straight wire shaped into a helix. Having about the same radiation characteristics, including gain, circular polarization, bandwidth, and side-lobe level, this new antenna occupies a volume more than 2.5 to 3 times smaller than the conventional helix. This reduction in size, which in turn may imply smaller weight and lower packaging and manufacturing costs, makes the proposed antenna very appealing to many communications and aerospace applications. / Master of Science

Demands for producing small components are increasing. Such components are usually produced using large-size conventional machining tools. This results in the inadequate usage of resources, including energy, space and time. In the 1990s, the concept of a microfactory was introduced in order to achieve better usage of these resources by scaling down the size of the machine tool itself. Several industries can benefit from implementing such a concept, such as the medical, automotive and electronics industries. A novel architecture for a reconfigurable micro-manufacturing cell (RMC) is presented in this research, aiming at delivering certain manufacturing strategies such as point of use (POU) and cellular manufacturing (CM) as well as several capabilities, including modularity, reconfigurability, mobility and upgradability. Unlike conventional machine tools, the proposed design is capable of providing several machining processes within a small footprint (500 mm2), yet processing parts within a volume up to 100 mm3. In addition, it delivers a rapid structure and process reconfiguration while achieving a micromachining level of accuracy. The approach followed in developing the system is highly iterative with several feedback loops. It was deemed necessary to adopt such an approach to ensure that not only was the design relevant, but also that it progresses the state-of-the-art and takes into account the many considerations in machine design. Following this approach, several design iterations have been developed before reaching a final design that is capable of delivering the required manufacturing qualities and operational performance. A prototype has been built based on the specifications of the selected design iteration, followed by providing a detailed material and components selection process and assembly method before running a performance assessment analysis of the prototype. At this stage, a correlation between the Finite Element Analysis (FEA) model and prototype has been considered, aiming at studying the level of performance of the RMC when optimising the design in the future. Then, based on the data collected during each stage of the design process, an optimisation process was suggested to improve the overall performance of the system, using computer aided design and modelling (CAD/CAM) tools to generate, analyse and optimise the design.

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This thesis explores the relationship between culture and human-centred design in Botswana, a topic on which there is little previous research. The pinnacle of good product innovation is when it is grounded on sensitive cultural analysis of users' culture; however, it has been observed that designers have not yet been able to encode cultural phenomena to the same extent as cognitive and physical human factors. The study develops a theoretical framework of cultural analysis, comparing traditional with contemporary socio-cultural factors that can be applied to designing products. The content analysis method was used to extract and synthesise traditional and contemporary socio-cultural factors from Botswana's cultural sources. An experimental study was undertaken in Botswana to investigate how socio-cultural factors can be integrated in product design, and the participants' challenge was to transfer and apply these into product features that reflect Botswana's culture. This data was analysed using the qualitative method of textual and visual content analysis. A culture-orientated design model has been proposed to assist designers to consciously integrate culture in their design practice. The framework demonstrates how to specify, analyse and integrate socio-cultural factors in the early stages of the design process by advancing local thought, content and solutions. It advances a new approach to design education, theory, research and practice. It emerged that culture can be used as a resource of information and a source of inspiration for product innovation that connects with users' traditions. The research findings show that culture-orientated products have meaningful content that reflects users' lifestyles as well as providing them with symbolic personal, social and cultural values, and that these aspects facilitate product acceptance.