Compact Planar Ultra-wideband Antennas for Ground Penetrating Radar

Compact and low-cost Ground Penetrating Radar (GPR) systems are attractive in detecting pavement layers and subsurface defects such as rebar corrosion at driving speed. Ultra-wideband (UWB) antennas are key elements for the high-speed operation of the aircoupled GPR systems. This thesis studies and develops a number of planar antennas that have been manufactured with low-cost printed circuit board (PCB) technology. It also presents a brief methodology for the design process in order to frame the context and boundary conditions of the antenna problem, and to satisfy the regulatory specifications such as FCC compliance.;A variety of compact low-profile UWB antennas are designed, fabricated, characterized and tested with GPR systems, including rounded Bowtie antenna, Bowtie slot antenna and Vivaldi antennas. All antennas are intended to operate within the 1.1 -- 4 GHz frequency band and benefit from compact size while providing high gain to allow for the detection of pavement layers and rebar in bridge decks to a depth of up to 2 feet. In-field measurements of the antennas, together with the GPR system, are presented for static testing scenarios such as buried rebar in a sand box and concrete slab. The antenna testing over the sand box and concrete slab demonstrates the great potential of utilizing the proposed antennas in air-coupled GPR systems, especially the compact rounded Bowtie and Bowtie slot antennas.;Antenna array is also developed to achieve enhanced penetrating capability of the GPR system while maintaining high resolution. When two Pacman antennas in the array are positioned in parallel, the gain of the array can be augmented up to 4 dB when compared to the original single Pacman application. Anti-parallel Pacman arrangement in the antenna array has also been proposed and tested, which could eliminate the ground reflection and direct coupling effectively due to the 180° phase difference between the two Pacmans in one antenna array.;The antenna dispersion problem is also summarized and clarified in detail with theoretical analysis, simulation models and experimental characterization to aid the UWB antenna development for impulsive GPR system.