Antennas: properties, designs, and optimization

The following sections discuss first the relevant parameters that characterize the radiation from antennas. Then, a set of frequently employed GPR antennas is briefly presented and explained in terms of these parameters. Finally, taking these geometries as a starting point of any antenna design, some recent GPR antenna designs are presented on the basis of computational optimization techniques. It should also be noted here that the same antennas are used for reception of signals, either using a single antenna for both purposes or separate antennas for transmission and reception. It is not necessary to discuss receiving antenna separately because, based on the reciprocity principle, the parameters are the same, that is, the basic electric properties such as impedance, bandwidth, efficiency, and radiation pattern are the same for both functions. The obvious difference is in the power levels but since antennas are typically very efficient, power radiated has little effect on the structure of the antenna.