Investigations of advanced folded reflectarray antennas

This paper reports on recent research on folded ref-lectarray antennas done at the University of Ulm. The first area of work deals with the investigations of reflector elements with improved phase angle range and the influence of different effects on bandwidth and antenna gain including cell type, size, or substrate layer structure. A second area of work is the precise characterization of reflector elements, both with respect to the phase angle as well as the polarization twisting. Two methods have been developed for such characterization at frequencies around 77 GHz, one based on a quasi-optical Gaussian beam setup, another one based on near-field probing.