A lightweight artificial dielectric for mitigating unwanted reflections and scattering at the soil-air dielectric boundary encountered by ground-penetrating radar
The development of an artificial dielectric is documented. The components of the finished product are 10 mm hollow polypropylene balls and 6 mm conducting beads. A method to separate—re-deploy the materials efficiently to achieve consistency of results is described. The material is placed over rough soil to make it look like smooth soil at the surface when illuminated by one antenna pair of a Focused Array Radar (FAR).
Experiments were conducted at Northeastern University, Boston, MA using an HP 8510 and Agilent 8714ES network analyzers, and Geo-centers, Inc., Newton, MA using one antenna-pair of a Focused Array Radar (FAR) system.
The HP 8510 used a paraffin-filled can as an open-ended waveguide to match artificial dielectric to soil, the Agilent 8714ES used WR284 waveguide to find the permittiviy of air, and a 3-1/8 inch E.I.A. coaxial transmission line to find permittivities of numerous materials (air, artificial dielectric of 2 different mixtures, dry sand, dry soil, bag moisture soil). The single antenna pair (send/receive) of a FAR system was used to verify the efficacy of the artificial dielectric under actual-use conditions.
The method used to characterize the real relative permittivity values in the coaxial system is described in detail. This method provided 10% accuracy across 700 to 1300 MHz.
Keywords: land-mine detection, artificial dielectric, ground penetrating radar, focused-array radar (FAR), cross-correlation, correlation coefficient, polypropylene, beads, real relative permittivity.
0544: Electrical engineering