A depolarizing reflector of Van Atta array design for polarimetric calibration

This paper proposes a novel depolarizing reflector for use in polarimetric radar calibration. The reflector is of Van Atta array design using dual-polarized elements, so the depolarized retransmitting beam from the reflector points automatically toward an incoming direction of a radar wave under calibration. Amplifiers can also be used in the reflector to increase its radar cross section. The proposed reflector thus exhibits simultaneously a depolarizing characteristic and a retrodirective characteristic. An investigation assuming an airborne and spaceborne polarimetric synthetic aperture radar is followed by an expression on the fundamental principle. An example shows that the L-band reflector of 1-m square with no amplifiers would be applicable to an airborne application. For a spaceborne application, however, amplifiers of 20-dB or more gain may be necessary to provide enough signal-to-background clutter ratio for calibration