Backscattering study on non-orthogonal trihedral corner reflectors

Synthetic aperture radar external calibration requires the use of trihedral corner reflectors deployed on test sites. Construction defects and mechanical stresses can affect the orthogonality of the corner reflector faces, with an effect on their radar cross-section. A model for evaluating backscattering properties of perfectly conductive trihedral corner reflectors, with internal angles deviating from orthogonality, has been developed. The combination of geometrical optics and physical optics methods has been used to calculate single, double and triple reflections. Moreover, the analysis takes into account single diffraction contributions which are described by means of the physical theory of diffraction. The radar cross-section of a set of trihedral corner reflectors with right, acute and obtuse angles has been then measured in an anechoic chamber. The numerical results and the experimental data are in excellent agreement, thus validating the model which foresees a decrease in the radar cross-section as a consequence of the orthogonality loss.