Mechanically Reconfigurable Folded Reflectarray Antenna for Variable Near-Field Focusing

A novel variable-focus near-field-focused (NFF) antenna implemented by mechanically reconfigurable folded reflectarray is proposed in this communication. The working principle is inspired by the concepts of folded reflectarray antenna (FRA) and Alvarez lens. The proposed antenna works at 15 GHz and consists of two parts. One part is a passive metasurface (MS), and the other part is an integrated part of array antenna, feed network, and another MS. By adjusting the relative position between the two parts, a variable focal length from 86 to 220 mm can be achieved. The design process is analyzed in detail and verified by simulation and experiment. The method proposed in this communication has the advantages of simple design and low cost, offering new possibilities for further NFF antenna systems.