Trihedral twist-grid polarimetric reflector

A novel retroreflector for use in a polarimetric radar system for precise navigation along a confined waterway is described. The reflector is designed to have a distinctive polarisation signature to differentiate itself from the clutter environment around it. The key attributes of the reflector are its wide angular response (in both azimuth and elevation), passive (i.e. nonpowered) operation, high reflection efficiency, and the ability to modify incident polarisation in the same manner as performed by a dihedral reflector. The design principles and construction of the reflector are described and a geometrical model is used to predict its angular response. Laboratory measurements to support the theory are also included