Optimum corner reflectors for calibration of imaging radars

Trihedral corner reflectors are widely used as calibration targets for imaging radars because of their large RCS and extremely wide RCS pattern. The maximum RCS of a trihedral is proportional to the physical size of its panels, thus trihedrals with large RCS are heavy and difficult for field deployment. In addition, the large physical dimensions usually cause uncertainty in the expected RCS of the trihedral. Another source of uncertainty in the RCS of a trihedral sitting on a ground plane is the coherent interaction of the ground plane with the trihedral. In the analysis of the trihedral, it is found that only a portion of panels contribute to the backscatter and therefore the size of the trihedral can be reduced without reducing RCS value significantly. A class of corner reflectors which will be referred to as self-illuminating corner reflectors is introduced and proposed as calibration targets. The panel area of those reflectors is 2/3 of that of the trihedral with the same RCS. It is shown that the reduction in panel size also reduces the uncertainty in the RCS value.