Reconfigurable reflectarray antenna using single-layer radiator controlled by PIN diodes

A new type of pattern-reconfigurable reflectarray phased by reconfigurable unit cells that are centrally controlled by a laptop is presented. The proposed reflectarray with single-layer radiators employs a phasing element formed by a fixed-size circular ring attached by a variable-length arc phase delay line controlled by positive-intrinsic-negative diodes. The biasing network of the diodes is properly designed to minimise the interference between the radiating structure and the biasing circuit. To that end, the biasing circuit is placed on a substrate layer below the ground plane whereas the PIN switching diodes are embedded within radiators. The biasing signal is transmitted to the switching elements at the top layer using vias that penetrate the thin substrate layer, the foam layer and the ground plane. Investigations are carried out to verify the performances of the phasing element using a waveguide simulator. A reflectarray, which includes a C-band offset fed 8 × 8 elements, is configured to switch its main beam between 20° and 30° from the broadside direction. A biasing control unit is added to the fabricated reflectarray and activated using a laptop. The measured radiation patterns of the proposed reflectarray demonstrate a beam-switching characteristic from the broadside direction, which confirm the proposed design method.