UCLA

The Global Positioning System (GPS) opened for general usage in the 1980s and has since led to the rapid growth of GPS receivers in both types and numbers. The proliferation prompted applications in various domains and on platforms with special requirements and constraints. Precise positioning is especially critical in drones and other autonomous platforms for tracking and fleet management. One primary source of error in the precision of GPS positioning is multipath interference; typically, antennas that resolve multipath issues involves large, expensive, and specially-designed ground planes, such as choke rings. Patch antennas are still among the most commonly used antenna designs for GPS receivers; their compact size, flexibility in design, low-cost, and low-complexity manufacturing give them unique advantages that are hard to rival by other antenna types. This thesis investigates the potential of a low-cost, shorted-annular-ring (SAR) reduced-surface-wave (RSW) patch antenna design, with multipath mitigation characteristics, for high-precision positioning of freight-carrying autonomous rail transport vehicles. General considerations for GPS antenna designs and SAR antenna design principles are presented. Several simulation studies are conducted for single- and dual-band (L1 & L2) antenna designs. A L1-band SAR-RSW antenna is prototyped and measured, and compared to simulation. The radiation characteristics of the proposed design is also assessed through simulations near a side plate that models the freight container.