Point-to-Point to Zone Plate: A Two-Stage Design Methodology for Planar Reflectors Enhancing mmWave/THz Coverage

The deployment of millimeter-wave (mmWave) and terahertz (THz) frequencies is essential for meeting the highthroughput and low-latency demands of 6G networks. However, the severe path loss and susceptibility to blockage at these frequencies create significant coverage challenges. While passive reflectors offer a low-cost, zero-power solution to bypass obstacles, conventional flat or simply curved reflectors provide limited control over the reflected field, failing to efficiently illuminate specific target areas. This paper presents a novel design methodology for a completely flat, passive reflector capable of advanced, custom beam-shaping. The design is a two-stage process. First, a custom-contoured surface, termed a point-topoint (P2P) reflector, is numerically synthesized to optimally redirect energy from a transmitter to a predefined coverage zone. Second, the phase profile of this contoured surface is transformed into a planar, binary pattern using the zone plate (ZP) concept, resulting in a low-profile reflector that is simple to fabricate using techniques like conductive ink printing. The performance of the proposed design is validated through full-wave simulations. The simulation results demonstrate that the ZP reflector significantly outperforms a conventional flat reflector in uniformly illuminating a designated region, establishing it as a promising on-demand solution for targeted coverage enhancement in future mmWave and THz wireless systems.