Antenna footprint measurements of stepped frequency CW radar on the air/ground interface [GPR for landmine detection]

This paper presents the antenna footprint measurements of a stepped frequency continuous wave radar. To image a subsurface, a knowledge of the wave fields radiated by the radar below the surface is necessary. Due to the complexity of the system it is hard to compute the emitted wave fields accurately in the ground. A remedy for this problem could be measurement of the antenna footprints on the air/ground interface and then apply synthetic propagation of the wave fields into the subsurface by using the Huygens principle. The footprint of a spiral antenna has been measured by using a 1 cm shielded loop antenna as a probe antenna positioned on the air/ground interface. Subsequently, the same measurement is repeated by positioning the probe in free space at the same elevation as the air/ground interface in order to analyse the correspondence between the measurements. The footprint patterns obtained after performing calibrations were comparable for both measurements.