Performance of Hybrid and Single-Frequency Impulse GPR Antennas on USGA Sporting Green
Freeland, R. S., B. Allred, D. Gamble, L. Martinez, B. Jones, and E. McCoy.  2016.  Journal of Environmental and Engineering Geophysics, 21(2), 57-65.

The utility of employing ground-penetrating radar (GPR) technologies for environmental surveys can vary, depending upon the physical properties of the site. Environmental conditions can fluctuate, altering soil properties. Operator proficiency and survey methodology will also influence GPR findings. Therefore, GPR equipment performance evaluation involves standardized tests that are frequently conducted indoors within laboratory-controlled environments. This study uses outdoor United States Golf Association (USGA) putting greens as a structure for GPR testing for surveying practitioners. These USGA putting greens provide a tightly controlled environment because many golf courses and sports turf fields adhere to strict USGA construction and irrigation guidelines. Past studies on several USGA greens show that GPR provided precise and accurate profiles of root-mixture depth, gravel-blanket thickness, and drain-tile layout. Results are independent of locale, as all USGA putting greens are virtually identical. In this project, the performance of various GPR antenna frequencies on USGA greens was assessed. This research determined that an efficient antenna for routine profiling of turf putting greens is in the 400- to 800-MHz range. Other frequencies also performed well for a particular target or task, such as for profiling sub-grade depths. The study also compared the performance of a hybrid antenna design with the performance of fixed-frequency antennas and found that the hybrid frequencies fit well for profiling turf greens. Greens management staff may have concerns regarding damage to high-value turf from geophysical survey trafficking. Proposed surveying practices and procedures can help lessen these concerns.