Plan resolution improves as attenuation increases, assuming that there is sufficient
signal to discriminate under the prevailing clutter conditions. In low attenuation media
the resolution obtained by the horizontal scanning technique is degraded, but under
these conditions the use of advanced signal processing techniques becomes feasible.
These techniques typically require measurements made using transmitter and receiver
pairs at a number of antenna positions to generate a synthetic aperture or focus the
image. Unlike conventional radars, which generally use a single antenna, most GPR
systems use separate transmit and receive antennas in what has been termed a bistatic
mode. However, as the antenna configuration is normally mobile, the term bistatic is
not really relevant.