Antenna system design for FMCW avalanche radar

• Main Author: Mohd Isa, F. N.
• Published: University College London (University of London) 2012
• Subjects: 621.3
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625893

Avalanches pose a significant threat to human life and settlements, hence their study is key in formulating settlement risk zones. Validating models of avalanches, developed to predict their behaviour, are limited by the quality of current field data. University College London (UCL) has developed a sophisticated FMCW phased array raday with sub-metre range resolution for imaging avalanches. The radar is installed in a bunker in an avalanche test facility in Valleé de La Sionne (VDLS) and has been gathering data since winter 2009. Due to space constraint and destructive issues with the bunker, a design for compact, low-cost and directive antenna is crucial to be used with the avalanche radar. This thesis documents the theory, analysis, design and measurement of the compact, low-cost and directive antennas. First, the parameter and location of VDLS is scrutinized to determine the characteristics that needs to be fulfilled when designing the antennas. Some of the parameters that were looked into are the operating frequency, the beamwidth of the antenna and the effects of placing the antenna in an array. Then, the study of the first antenna, a multilayer microstrip patch antenna with novel feeding method is presented. The directive concept of the antenna is obtained using an array of 4 x 2 patches, with increased antenna height and a novel feeding technique. The antenna is then fabricated using Rogers RT Duroid 5880 and assembled to be measured and compared with the simulated version. The second antenna proposed in this thesis is an array of microstrip Yagi antenna. The directive concept of this antenna is achieved through the design of the microstrip Yagi antenna itself and applying the antenna in an array of linear arrangement. The antenna is then fabricated using Rogers RT Duroid 5880 and compared with the simulated version. Finally, the first antenna characteristics is being exploited in series of Matlab program to estimate the antenna performance in a sparsely-populated phased array system. It has been demonstrated experimentally and through measurement that the antenna system design is suitable for the application of FMCW avalanche radar.