Usually the most important factors are vertical resolution and depth of radar penetration.  These are achieved by using the appropriate frequency antenna (80-900 MHz).  Detailed work on concrete thickness or location of buried rebar, tanks, wires, or small voids would require the 900 MHz antenna; conversely, location of deep clay layers or buried channels would require the 80-120 MHz antenna.

If lateral resolution is not critical, ie, mapping large areas for geological features, the (80-300 MHz) antenna may be towed behind a truck or 4x4 RV.  The system electronics and power supplies are placed in the vehicle and connected to the antenna by a shielded cable.  For critical applications, the antenna should be moved across the site by hand or a slow, steady winch system; this mode of acquisition will provide accurate locations of buried tanks, pipes, trenches and/or drums.  For long profiles, the electronics may be moved on a cart with the antenna.

Geosphere's investigations using GPR are regularly done with one of Geophysical Survey Systems Inc.'s (GSSI) SIR-3 systems. The setup includes one of three antennas (120MHz, 300MHz or 900MHz) and a profiling recorder to handle the incoming radar pulses. System settings and filters are used to maximize the useful radar signals to background or geologic "noise" in the overall radar record; this includes removing unwanted static and broad-band frequency effects.  Geosphere, however, limits the amount of filtering during data acquisition as unrecognized signals may inadvertently be lost.

Project objectives and site conditions will generally determine the radar configuration used for the survey; these considerations include:

• antenna frequency: depth, resolution, shielding
  
• antenna movement: lateral resolution, profile length
  
• system & settings: interferences, processing needed