Magnetic Antenna Ground Penetrating Radar Lava Tube Detection Use Case and Property Estimation.

Traditional Ground Penetrating Radar (GPR) systems rely on antennae driven by the electric field component of the resonant electromagnetic waves they employ. While effective, these systems often suffer from bulkiness and limited adaptability in constrained environments. By contrast, antennae driven by the magnetic field component present several distinct advantages. These include a significantly more compact design, and a modest increase in operational bandwidth. To explore these benefits, we have developed and tested a compact ferromagnetic core antenna based GPR system. This prototype demonstrated comparable depth penetration and resolution to traditional electric antenna-based systems, but with a much smaller form factor, making it particularly well-suited for applications where space and weight constraints are critical.

The Undara Volcanic National Park in Northern Queensland, Australia, is home to one of the most extensive lava tube networks in the world, stretching over an estimated 160 kilometres. These tubes were formed by basaltic lava flows around 190,000 years ago, leaving behind vast subterranean passageways. We conducted field tests of our magnetic antenna based GPR system in a section of the Undara network, specifically at the Stephenson’s and Ewamian Caves. These caves, part of the lava tube system, are accessible via collapsed sections known as skylights, providing an ideal natural testbed for evaluating the system’s performance.

Accurate material property estimation is essential for understanding the lithology of surveyed areas, as properties like dielectric permittivity and electrical conductivity are directly influenced by a rock’s mineral composition, texture, and porosity. These properties can serve as proxies for broader lithological characteristics, offering valuable insights into subsurface geology. To expand the potential of GPR systems, we explored combining electric and magnetic field components from simulation data. This dual-component approach aims to uncover additional subsurface properties, enhancing the accuracy and detail of geological interpretations. Further, we are investigating how this combined methodology can be applied to real-world data, potentially revolutionizing subsurface exploration in both terrestrial and extraterrestrial environments.